Slides from Massimo Oliviero talk @Codemotion Roma 2014

1. Modernizes your
Objective-C
Massimo Oliviero!
Software Developer
@maxoly

2. About
Massimo Oliviero
Freelance Software Developer & Trainer
#pragma mark founder
!
www.massimooliviero.net
massimo.oliviero@gmail.com
@maxoly

3. #pragma mark
iOS & OSX Developers Community
We organize the #PragmaConference, an event
dedicated to iOS and OS X development
!
http://www.pragmamark.org
http://www.facebook.com/groups/pragmamark
@pragmamarkorg

4. Agenda

5. Agenda
‣ Syntax

6. Agenda
‣ Syntax
‣ Conventions

7. Agenda
‣ Syntax
‣ Conventions
‣ Coding

8. Agenda
‣ Syntax
‣ Conventions
‣ Coding
‣ Framework

9. Syntax

10. use new literal syntax
you can create NSArray, NSDictionary, NSNumber with a simple @

11. Literals
NSArray *names = [NSArray
arrayWithObjects:@"Marco", @"Paolo", @"Flavio", nil];
NSDictionary *jobs = [NSDictionary
dictionaryWithObjectsAndKeys:@"Marco", @"CTO", @"Paolo", "CEO", nil];
NSNumber *one = [NSNumber numberWithInt:1];
NSNumber *boolNum = [NSNumber numberWithBool:YES];
NSNumber *square = [NSNumber numberWithDouble:sqrt(2)];

12. Literals
NSArray *names = [NSArray
arrayWithObjects:@"Marco", @"Paolo", @"Flavio", nil];
NSDictionary *jobs = [NSDictionary
dictionaryWithObjectsAndKeys:@"Marco", @"CTO", @"Paolo", "CEO", nil];
NSNumber *one = [NSNumber numberWithInt:1];
NSNumber *boolNum = [NSNumber numberWithBool:YES];
NSNumber *square = [NSNumber numberWithDouble:sqrt(2)];
NSArray *names = @[ @"Marco", @"Paolo", @"Giuseppe" ];
!
NSDictionary *jobs = @{ @"CTO" : @"Marco", @"CEO" : @"Paolo" };
!
NSNumber *one = @1;
NSNumber *boolNum = @YES;
NSNumber *square = @(sqrt(2));

13. Literals

14. Literals
‣ The new object literals significantly reduce the
verbosity of code

15. Literals
‣ The new object literals significantly reduce the
verbosity of code
‣ All objects made via literal (such an array or a
dictionary) are immutable

16. Literals
‣ The new object literals significantly reduce the
verbosity of code
‣ All objects made via literal (such an array or a
dictionary) are immutable
‣ Remember that @(expr) dynamically evaluates the
boxed expression and returns the appropriate object
literal based on its value

17. use Object Subscripting
Object pointer values can now be used with C’s subscripting operator

18. Object Subscripting
!
NSArray *people = @[ @"John", @"Steve", @"Bill" ];
NSString *steve = [people objectAtIndex:1];
NSDictionary *books = @{ @"123" : @"Odyssey", @"234" : @"Illiad" };
NSString *illiad = [books objectForKey:@“234"];
!
// Mutable
NSMutableArray *mPeople = [people mutableCopy];
[mPeople addObject:@"Ive"];
NSMutableDictionary *mBooks = [books mutableCopy];
[mBooks setObject:@"Othello" forKey:@"876"];

19. Object Subscripting
!
NSArray *people = @[ @"John", @"Steve", @"Bill" ];
NSString *steve = [people objectAtIndex:1];
NSDictionary *books = @{ @"123" : @"Odyssey", @"234" : @"Illiad" };
NSString *illiad = [books objectForKey:@“234"];
!
// Mutable
NSMutableArray *mPeople = [people mutableCopy];
[mPeople addObject:@"Ive"];
NSMutableDictionary *mBooks = [books mutableCopy];
[mBooks setObject:@"Othello" forKey:@"876"];
!
NSArray *people = @[ @"John", @"Steve", @"Bill" ];
NSString *steve = people[1];
NSDictionary *books = @{ @"123" : @"Odyssey", @"234" : @"Illiad" };
NSString *illiad = books[@"234"];
!
!
// Mutable
NSMutableArray *mPeople = [people mutableCopy];
mPeople[3] = @"Ive";
NSMutableDictionary *mBooks = [books mutableCopy];
mBooks[@"876"] = @"Othello";

20. Custom Subscripting

21. Custom Subscripting
@interface MGACustomer : NSObject
@property (nonatomic, strong, readonly) NSArray *orders;
// Custom Indexed Subscripting
- (id)objectAtIndexedSubscript:(NSUInteger)idx;
- (void)setObject:(id)obj atIndexedSubscript:(NSUInteger)idx;
// Custom Keyed Subscripting
- (id)objectForKeyedSubscript:(id <NSCopying>)key;
- (void)setObject:(id)obj forKeyedSubscript:(id <NSCopying>)key;
@end
// how to use custom subscripting
- (void)foo
{
MGACustomer *customer = [[MGACustomer alloc] init];
id order67 = customer[67];
id order34 = customer[@"order.34"];
}

22. Object Subscripting

23. Object Subscripting
‣ Subscripting syntax can significantly reduce the
verbosity of code that deals heavily with arrays and
dictionaries

24. Object Subscripting
‣ Subscripting syntax can significantly reduce the
verbosity of code that deals heavily with arrays and
dictionaries
‣ Syntax similar to that found in common scripting
languages

25. Object Subscripting
‣ Subscripting syntax can significantly reduce the
verbosity of code that deals heavily with arrays and
dictionaries
‣ Syntax similar to that found in common scripting
languages
‣ You can extend your own classes with subscripting
support

26. use new @import declaration
@import is the new compiler directive introduced by Modules

27. @import
#import <UIKit/UIKit.h>
#import <MapKit/MapKit.h> // you must add framework from Target > Build Phases
!
!
@interface MGAMapViewController : UIViewController
!
@property (weak, nonatomic) IBOutlet MKMapView *mapView;
!
@end

28. @import
#import <UIKit/UIKit.h>
#import <MapKit/MapKit.h> // you must add framework from Target > Build Phases
!
!
@interface MGAMapViewController : UIViewController
!
@property (weak, nonatomic) IBOutlet MKMapView *mapView;
!
@end
@import UIKit;
@import MapKit; // no additional steps required
!
!
@interface MGAMapViewController : UIViewController
!
@property (weak, nonatomic) IBOutlet MKMapView *mapView;
!
@end

29. @import

30. @import
‣ Modules provide an alternative, simpler way to use
software libraries that provides better compile-time
scalability and eliminates many of the problems
inherent to using the C preprocessor to access the API
of a library

31. @import
‣ Modules provide an alternative, simpler way to use
software libraries that provides better compile-time
scalability and eliminates many of the problems
inherent to using the C preprocessor to access the API
of a library
‣ Modules link frameworks automatically (no more
need to link framework from Build Phases)

32. @import
‣ Modules provide an alternative, simpler way to use
software libraries that provides better compile-time
scalability and eliminates many of the problems
inherent to using the C preprocessor to access the API
of a library
‣ Modules link frameworks automatically (no more
need to link framework from Build Phases)
‣ At this time, modules are only available for Apple’s
frameworks and have been implicitly disabled for C++

33. use new type instancetype
instancetype is a contextual keyword that can be used as a result type to signal that a
method returns a related result type, you can use it as return type of an init method or
a (convenient)constructor

34. instancetype
@interface MGACustomer : NSObject
!
@property (nonatomic, readwrite, copy) NSString *name;
+ (id)customerWithName:(NSString *)name;
!
@end
!
@implementation MGACustomer
!
+ (id)customerWithName:(NSString *)name
{
id user = [[self alloc] init];
[user setName:name];
return user;
}
!
@end
!
!
!
!
!
!
!
!

35. instancetype
@interface MGACustomer : NSObject
!
@property (nonatomic, readwrite, copy) NSString *name;
+ (id)customerWithName:(NSString *)name;
!
@end
!
@implementation MGACustomer
!
+ (id)customerWithName:(NSString *)name
{
id user = [[self alloc] init];
[user setName:name];
return user;
}
!
@end
!
!
!
!
!
!
!
!
@interface MGACustomer : NSObject
!
@property (nonatomic, readwrite, copy) NSString *name;
+ (id)customerWithName:(NSString *)name;
!
@end
!
@implementation MGACustomer
!
+ (id)customerWithName:(NSString *)name
{
id user = [[self alloc] init];
[user setName:name];
return user;
}
!
@end
!
..
!
- (void)foo
{
// assign an object of type MGACustomer to a string variable
// will not generate any error or warning at compile-time
NSString *wrong = [MGACustomer customerWithName:@"test"];
}

36. instancetype
@interface MGACustomer : NSObject
!
@property (nonatomic, readwrite, copy) NSString *name;
+ (id)customerWithName:(NSString *)name;
!
@end
!
@implementation MGACustomer
!
+ (id)customerWithName:(NSString *)name
{
id user = [[self alloc] init];
[user setName:name];
return user;
}
!
@end
!
!
!
!
!
!
!
!
@interface MGACustomer : NSObject
!
@property (nonatomic, readwrite, copy) NSString *name;
+ (id)customerWithName:(NSString *)name;
!
@end
!
@implementation MGACustomer
!
+ (id)customerWithName:(NSString *)name
{
id user = [[self alloc] init];
[user setName:name];
return user;
}
!
@end
!
..
!
- (void)foo
{
// assign an object of type MGACustomer to a string variable
// will not generate any error or warning at compile-time
NSString *wrong = [MGACustomer customerWithName:@"test"];
}
@interface MGACustomer : NSObject
!
@property (nonatomic, readwrite, copy) NSString *name;
+ (instancetype)customerWithName:(NSString *)name;
!
@end
!
@implementation MGACustomer
!
+ (instancetype)customerWithName:(NSString *)name
{
id user = [[self alloc] init];
[user setName:name];
return user;
}
!
@end
!
..
!
- (void)foo
{
// With ‘instancetype’ the compiler could infer type, it will generate: Incompatible
// pointer types initializing 'NSString *' with an expression of type 'MGACustomer *'
NSString *wrong = [MGACustomer customerWithName:@"test"];
}

37. instancetype

38. instancetype
‣ With instancetype, the compiler will correctly infer
that the result of convenient constructor is an
instance of a MGACustomer

39. instancetype
‣ With instancetype, the compiler will correctly infer
that the result of convenient constructor is an
instance of a MGACustomer
‣ Instancetype, unlike id, can only be used as the result
type in a method declaration

40. instancetype
‣ With instancetype, the compiler will correctly infer
that the result of convenient constructor is an
instance of a MGACustomer
‣ Instancetype, unlike id, can only be used as the result
type in a method declaration
‣ Init method should also use instancetype instead of
id, instancetype is more explicit and therefore better
than id

41. use auto property synthesis
synthesize not necessary for @property since Xcode 4.4

42. auto property synthesis
@interface MGACustomer : NSObject
!
@property (nonatomic, readwrite, copy) NSString *name;
@property (nonatomic, readwrite, copy) NSString *address;
!
@end
!
!
!
!
@implementation MGACustomer
{
NSString *_name;
NSString *_address;
}
!
@synthesize name = _name;
@synthesize address = _address;
!
- (void)foo
{
_name = @"Apple Inc.";
}
!
@end

43. auto property synthesis
@interface MGACustomer : NSObject
!
@property (nonatomic, readwrite, copy) NSString *name;
@property (nonatomic, readwrite, copy) NSString *address;
!
@end
!
!
!
!
@implementation MGACustomer
{
NSString *_name;
NSString *_address;
}
!
@synthesize name = _name;
@synthesize address = _address;
!
- (void)foo
{
_name = @"Apple Inc.";
}
!
@end
@interface MGACustomer : NSObject
!
@property (nonatomic, readwrite, copy) NSString *name;
@property (nonatomic, readwrite, copy) NSString *address;
!
@end
!
!
!
!
@implementation MGACustomer
!
!
// compiler auto-synthesizes properties for you
// and generate corresponding ivar(s)
// with underscore as prefix
!
!
!
- (void)foo
{
_name = @"Apple Inc.”; // you can still access to ivar
}
!
@end

44. auto property synthesis

45. auto property synthesis
‣ Clang provides support for autosynthesis of declared
properties. Using this feature, clang provides default
synthesis of those properties not declared @dynamic
and not having user provided backing getter and
setter methods.

46. auto property synthesis
‣ Clang provides support for autosynthesis of declared
properties. Using this feature, clang provides default
synthesis of those properties not declared @dynamic
and not having user provided backing getter and
setter methods.
‣ Auto-synthesis is not support for properties defined in
a protocol

47. auto property synthesis
‣ Clang provides support for autosynthesis of declared
properties. Using this feature, clang provides default
synthesis of those properties not declared @dynamic
and not having user provided backing getter and
setter methods.
‣ Auto-synthesis is not support for properties defined in
a protocol
‣ The compiler will add the ivar for you (with underscore
prefix) when it adds the required accessor methods

48. use copy for any immutable class
for attributes whose type is an immutable value class that conforms to the
NSCopying protocol (e.g.. NSDate, NSNumber, NSArray, NSSet), you almost always
should specify copy in your @property declaration

49. copy attribute
!
!
@interface MGACustomer : NSObject
!
@property (nonatomic, readwrite, strong) NSString *name;
@property (nonatomic, readwrite, strong) NSString *address;
@property (nonatomic, readwrite, strong) NSArray *orders;
@property (nonatomic, readwrite, strong) NSDate *created;
!
@end
!

50. copy attribute
!
!
@interface MGACustomer : NSObject
!
@property (nonatomic, readwrite, strong) NSString *name;
@property (nonatomic, readwrite, strong) NSString *address;
@property (nonatomic, readwrite, strong) NSArray *orders;
@property (nonatomic, readwrite, strong) NSDate *created;
!
@end
!
!
!
@interface MGACustomer : NSObject
!
@property (nonatomic, readwrite, copy) NSString *name;
@property (nonatomic, readwrite, copy) NSString *address;
@property (nonatomic, readwrite, copy) NSArray *orders;
@property (nonatomic, readwrite, copy) NSDate *created;
!
@end
!

51. copy attribute

52. copy attribute
‣ The reason of copy is that it is possible to have a
property that is declared as an immutable type (such
as NSString) yet pass it a mutable type (such as
NSMutableString). In which case it is possible to
change the property from outside the class

53. copy attribute
‣ The reason of copy is that it is possible to have a
property that is declared as an immutable type (such
as NSString) yet pass it a mutable type (such as
NSMutableString). In which case it is possible to
change the property from outside the class
‣ using copy is recommended, because it behaves
sensibly with class clusters, sending copy to a mutable
class returns an immutable copy of the object

54. NS_ENUM & NS_OPTIONS macro
these macros are the new, preferred way to declare enum types.

55. NS_ENUM
typedef enum MGAUserProfile : NSUInteger
{
MGAUserProfileAdmin,
MGAUserProfileGuest,
MGAUserProfileOperator
} MGAUserProfile;
!
!
!
@interface MGACustomer : NSObject
!
@property (nonatomic, readwrite, assign) MGAUserProfile profile;
!
@end

56. NS_ENUM
typedef enum MGAUserProfile : NSUInteger
{
MGAUserProfileAdmin,
MGAUserProfileGuest,
MGAUserProfileOperator
} MGAUserProfile;
!
!
!
@interface MGACustomer : NSObject
!
@property (nonatomic, readwrite, assign) MGAUserProfile profile;
!
@end
typedef NS_ENUM(NSUInteger, MGAUserProfile)
{
MGAUserProfileAdmin,
MGAUserProfileGuest,
MGAUserProfileOperator
};
!
!
!
@interface MGACustomer : NSObject
!
@property (nonatomic, readwrite, assign) MGAUserProfile profile;
!
@end

57. NS_OPTIONS
typedef enum MGAUserProfile : NSUInteger
{
MGAUserProfileAdmin = 1 << 0,
MGAUserProfileGuest = 1 << 1,
MGAUserProfileOperator = 1 << 2
} MGAUserProfile;
!
!
!
@interface MGACustomer : NSObject
!
@property (nonatomic, readwrite, assign) MGAUserProfile profile;
!
@end

58. NS_OPTIONS
typedef enum MGAUserProfile : NSUInteger
{
MGAUserProfileAdmin = 1 << 0,
MGAUserProfileGuest = 1 << 1,
MGAUserProfileOperator = 1 << 2
} MGAUserProfile;
!
!
!
@interface MGACustomer : NSObject
!
@property (nonatomic, readwrite, assign) MGAUserProfile profile;
!
@end
typedef NS_OPTIONS(NSUInteger, MGAUserProfile)
{
MGAUserProfileAdmin = 1 << 0,
MGAUserProfileGuest = 1 << 1,
MGAUserProfileOperator = 1 << 2,
};
!
!
!
@interface MGACustomer : NSObject
!
@property (nonatomic, readwrite, assign) MGAUserProfile profile;
!
@end

59. NS_ENUM & NS_OPTIONS

60. NS_ENUM & NS_OPTIONS
‣ The new macros combines the best of all ways to
declare an enum or an option, and even provide hints
to the compiler for type-checking and switch
statement completeness.

61. NS_ENUM & NS_OPTIONS
‣ The new macros combines the best of all ways to
declare an enum or an option, and even provide hints
to the compiler for type-checking and switch
statement completeness.
‣ If the compiler is operating in C++11 or Objective-C+
+11 mode, the macros behave slightly differently in
order to make the code compatible with the mixed
mode

62. use extern const not #define
the best way to define a globally accessible constant is extern const

63. extern const

64. // Constants.h
#define kMGAProjectConst @“myString"
#define kMGASomeMagicValue 42
extern const

65. // Constants.h
#define kMGAProjectConst @“myString"
#define kMGASomeMagicValue 42
extern const
// Constants.h
extern NSString * const kMGAProjectConst;
extern CGFloat const kMGASomeMagicValue;
// Constants.m
#import “Constants.h"
NSString * const kMGAProjectConst = @“server.com”;
CGFloat const kMGASomeMagicValue = 42.0f;

66. // Constants.h
#define kMGAProjectConst @“myString"
#define kMGASomeMagicValue 42
extern const
// Constants.h
extern NSString * const kMGAProjectConst;
extern CGFloat const kMGASomeMagicValue;
// Constants.m
#import “Constants.h"
NSString * const kMGAProjectConst = @“server.com”;
CGFloat const kMGASomeMagicValue = 42.0f;
// Constants.h
FOUNDATION_EXPORT NSString * const kMGAProjectConst;
FOUNDATION_EXPORT CGFloat const kMGASomeMagicValue;
!
!
!
// Constants.m
#import “Constants.h"
!
NSString * const kMGAProjectConst = @“server.com”;
CGFloat const kMGASomeMagicValue = 42.0f;

67. extern const

68. extern const
‣ It ensures that the compiler do a static type
checking and emit a warning if you try to use it
somewhere where it isn't expecting

69. extern const
‣ It ensures that the compiler do a static type
checking and emit a warning if you try to use it
somewhere where it isn't expecting
‣ One benefit is that changing the value of a constant
does not cause a rebuild of your entire program.

70. extern const
‣ It ensures that the compiler do a static type
checking and emit a warning if you try to use it
somewhere where it isn't expecting
‣ One benefit is that changing the value of a constant
does not cause a rebuild of your entire program.
‣ Use FOUNDATION_EXPORT macro instead of extern
if your code will be used in mixed C/C++
environments or on other platforms

71. use Foundation Data Types
if you are unsure, the Foundation Data Types (like NSInterger or CGFloat) are the best
choice because they are architecture safe versions of the corresponding C types

72. Foundation Data Types

73. Foundation Data Types
‣ The Fondation Data Types were introduced to make it
easier to write code that works on both 32-bit and 64-
bit without modification

74. Foundation Data Types
‣ The Fondation Data Types were introduced to make it
easier to write code that works on both 32-bit and 64-
bit without modification
‣ You usually want to use Foundation Data Types when
you don't know what kind of processor architecture
your code might run on

75. Foundation Data Types
‣ The Fondation Data Types were introduced to make it
easier to write code that works on both 32-bit and 64-
bit without modification
‣ You usually want to use Foundation Data Types when
you don't know what kind of processor architecture
your code might run on
‣ However, if you need to take control on memory
footprint you can use native types

76. Use Class Extensions to Hide Private Data
Class extensions are often used to extend the public interface with additional private
methods, properties or ivars for use within the implementation of the class itself

77. // MGAMapViewController.h
@interface MGAMapViewController : UIViewController
!
!
!
@end
!
// MGAMapViewController.m
@interface MGAMapViewController ()
!
!
!
!
!
!
!
!
@end
!
@implementation MGAMapViewController
!
!
!
!
!
!
!
!
!
@end
Class Extensions

78. // MGAMapViewController.h
@interface MGAMapViewController : UIViewController
!
!
!
@end
!
// MGAMapViewController.m
@interface MGAMapViewController ()
!
!
!
!
!
!
!
!
@end
!
@implementation MGAMapViewController
!
!
!
!
!
!
!
!
!
@end
// MGAMapViewController.h
@interface MGAMapViewController : UIViewController
!
!
!
@end
!
// MGAMapViewController.m
@interface MGAMapViewController ()
!
!
!
!
- (void)privateMethod;
!
!
!
@end
!
@implementation MGAMapViewController
!
!
!
!
- (void)privateMethod
{
}
!
@end
Class Extensions

79. // MGAMapViewController.h
@interface MGAMapViewController : UIViewController
!
!
!
@end
!
// MGAMapViewController.m
@interface MGAMapViewController ()
!
!
!
!
!
!
!
!
@end
!
@implementation MGAMapViewController
!
!
!
!
!
!
!
!
!
@end
// MGAMapViewController.h
@interface MGAMapViewController : UIViewController
!
!
!
@end
!
// MGAMapViewController.m
@interface MGAMapViewController ()
!
!
!
!
- (void)privateMethod;
!
!
!
@end
!
@implementation MGAMapViewController
!
!
!
!
- (void)privateMethod
{
}
!
@end
// MGAMapViewController.h
@interface MGAMapViewController : UIViewController
!
!
!
@end
!
// MGAMapViewController.m
@interface MGAMapViewController ()
{
NSString *privateString;
}
!
- (void)privateMethod;
!
!
!
@end
!
@implementation MGAMapViewController
!
!
!
!
- (void)privateMethod
{
privateString = @"hello";
}
!
@end
Class Extensions

80. // MGAMapViewController.h
@interface MGAMapViewController : UIViewController
!
!
!
@end
!
// MGAMapViewController.m
@interface MGAMapViewController ()
!
!
!
!
!
!
!
!
@end
!
@implementation MGAMapViewController
!
!
!
!
!
!
!
!
!
@end
// MGAMapViewController.h
@interface MGAMapViewController : UIViewController
!
!
!
@end
!
// MGAMapViewController.m
@interface MGAMapViewController ()
!
!
!
!
- (void)privateMethod;
!
!
!
@end
!
@implementation MGAMapViewController
!
!
!
!
- (void)privateMethod
{
}
!
@end
// MGAMapViewController.h
@interface MGAMapViewController : UIViewController
!
!
!
@end
!
// MGAMapViewController.m
@interface MGAMapViewController ()
{
NSString *privateString;
}
!
- (void)privateMethod;
!
!
!
@end
!
@implementation MGAMapViewController
!
!
!
!
- (void)privateMethod
{
privateString = @"hello";
}
!
@end
Class Extensions
// MGAMapViewController.h
@interface MGAMapViewController : UIViewController
!
@property (nonatomic, readonly) NSArray *points;
!
@end
!
// MGAMapViewController.m
@interface MGAMapViewController ()
{
NSString *privateString;
}
!
- (void)privateMethod;
!
@property (nonatomic, strong, readwrite) NSArray *points;
!
@end
!
@implementation MGAMapViewController
!
!
!
!
- (void)privateMethod
{
privateString = @"hello";
}
!
@end

81. // MGAMapViewController.h
@interface MGAMapViewController : UIViewController
!
!
!
@end
!
// MGAMapViewController.m
@interface MGAMapViewController ()
!
!
!
!
!
!
!
!
@end
!
@implementation MGAMapViewController
!
!
!
!
!
!
!
!
!
@end
// MGAMapViewController.h
@interface MGAMapViewController : UIViewController
!
!
!
@end
!
// MGAMapViewController.m
@interface MGAMapViewController ()
!
!
!
!
- (void)privateMethod;
!
!
!
@end
!
@implementation MGAMapViewController
!
!
!
!
- (void)privateMethod
{
}
!
@end
// MGAMapViewController.h
@interface MGAMapViewController : UIViewController
!
!
!
@end
!
// MGAMapViewController.m
@interface MGAMapViewController ()
{
NSString *privateString;
}
!
- (void)privateMethod;
!
!
!
@end
!
@implementation MGAMapViewController
!
!
!
!
- (void)privateMethod
{
privateString = @"hello";
}
!
@end
Class Extensions
// MGAMapViewController.h
@interface MGAMapViewController : UIViewController
!
@property (nonatomic, readonly) NSArray *points;
!
@end
!
// MGAMapViewController.m
@interface MGAMapViewController ()
{
NSString *privateString;
}
!
- (void)privateMethod;
!
@property (nonatomic, strong, readwrite) NSArray *points;
!
@end
!
@implementation MGAMapViewController
!
!
!
!
- (void)privateMethod
{
privateString = @"hello";
}
!
@end
// MGAMapViewController.h
@interface MGAMapViewController : UIViewController
!
@property (nonatomic, readonly) NSArray *points;
!
@end
!
// MGAMapViewController.m
@interface MGAMapViewController ()
{
NSString *privateString;
}
!
- (void)privateMethod;
!
@property (nonatomic, strong, readwrite) NSArray *points;
!
@end
!
@implementation MGAMapViewController
{
NSInteger counter;
}
!
- (void)privateMethod
{
privateString = @"hello";
}
!
@end

82. Class Extensions

83. Class Extensions
‣ A class extension bears some similarity to a category,
but it can only be added to a class for which you have
the source code at compile time. The methods
declared by a class extension are implemented in the
@implementation block for the original class

84. Class Extensions
‣ A class extension bears some similarity to a category,
but it can only be added to a class for which you have
the source code at compile time. The methods
declared by a class extension are implemented in the
@implementation block for the original class
‣ By declaring the class extension inside the source code
file for the class implementation, the information stays
private to the class; the header files in theory should
only expose public interface for your classes

85. Class Extensions

86. Class Extensions
‣ It’s possible to use a class extension to add custom
instance variables. These are declared inside braces in
the class extension interface

87. Class Extensions
‣ It’s possible to use a class extension to add custom
instance variables. These are declared inside braces in
the class extension interface
‣ It’s also common, for example, to define a property as
readonly in the interface, but as readwrite in a class
extension declared above the implementation, in order
that the internal methods of the class can change the
property value directly

88. Class Extensions
‣ It’s possible to use a class extension to add custom
instance variables. These are declared inside braces in
the class extension interface
‣ It’s also common, for example, to define a property as
readonly in the interface, but as readwrite in a class
extension declared above the implementation, in order
that the internal methods of the class can change the
property value directly
‣ It’s also possible to declare an ivar in the
@implemetation block

89. Conventions

90. use prefixes on all classes
classes must be named uniquely in order to avoid name clashes

91. use prefixes on all classes
@interface Customer : NSObject
!
@property (nonatomic, readwrite, copy) NSString *name;
@property (nonatomic, readwrite, copy) NSString *address;
!
@end
!
!
!
!
@interface HomeViewController : UIViewController
!
@property (weak, nonatomic) IBOutlet UILabel *userLabel;
@property (weak, nonatomic) IBOutlet UILabel *logoLabel;
@property (strong, nonatomic) Customer *user;
!
@end

92. use prefixes on all classes
@interface Customer : NSObject
!
@property (nonatomic, readwrite, copy) NSString *name;
@property (nonatomic, readwrite, copy) NSString *address;
!
@end
!
!
!
!
@interface HomeViewController : UIViewController
!
@property (weak, nonatomic) IBOutlet UILabel *userLabel;
@property (weak, nonatomic) IBOutlet UILabel *logoLabel;
@property (strong, nonatomic) Customer *user;
!
@end
@interface MGACustomer : NSObject
!
@property (nonatomic, readwrite, copy) NSString *name;
@property (nonatomic, readwrite, copy) NSString *address;
!
@end
!
!
!
!
@interface MGAHomeViewController : UIViewController
!
@property (weak, nonatomic) IBOutlet UILabel *userLabel;
@property (weak, nonatomic) IBOutlet UILabel *logoLabel;
@property (strong, nonatomic) MAGCustomer *user;
!
@end

93. use prefixes on all classes

94. use prefixes on all classes
‣ Choose a prefix with at least 3 uppercase chars that are
significant for the project

95. use prefixes on all classes
‣ Choose a prefix with at least 3 uppercase chars that are
significant for the project
‣ Two-letter prefixes are reserved by Apple for use in
framework classes, so you must use 3 (or more)

96. use prefixes on all classes
‣ Choose a prefix with at least 3 uppercase chars that are
significant for the project
‣ Two-letter prefixes are reserved by Apple for use in
framework classes, so you must use 3 (or more)
‣ Objective-C classes must be named uniquely not only within
the code that you’re writing in a project, but also across any
frameworks or bundles you might be including. As an
example, you should avoid using generic class names like
ViewController or TextParser because it’s possible a
framework you include in your app may fail to follow
conventions and create classes with the same names.

97. use a prefix for method names in categories
in a category you should include a prefix on the method name to avoid clashes

98. prefix category methods
!
@interface NSString (MGAAdditions)
!
- (NSString *)reverse;
- (NSString *)sha256;
!
@end

99. prefix category methods
!
@interface NSString (MGAAdditions)
!
- (NSString *)reverse;
- (NSString *)sha256;
!
@end
!
@interface NSString (MGAAdditions)
!
- (NSString *)mga_reverse;
- (NSString *)mga_sha256;
!
@end

100. prefix category methods

101. prefix category methods
‣ If the name of a method declared in a category is the same as a
method in the original class, or a method in another category
on the same class (or even a superclass), the behavior is
undefined as to which method implementation is used at
runtime.

102. prefix category methods
‣ If the name of a method declared in a category is the same as a
method in the original class, or a method in another category
on the same class (or even a superclass), the behavior is
undefined as to which method implementation is used at
runtime.
‣ In order to avoid undefined behavior, it’s best practice to add a
prefix to method names in categories on framework classes, just
like you should add a prefix to the names of your own classes.
You might choose to use the same three letters you use for your
class prefixes, but lowercase to follow the usual convention for
method names, then an underscore, before the rest of the
method name

103. properly define BOOL property
for Boolean properties the getter method should start with is

104. properly define BOOL property
!
@interface MGAUser
!
@property (nonatomic, assign) BOOL authenticated;
!
@end
!
@interface MGAUser
!
@property (nonatomic, assign, getter = isAuthenticated) BOOL authenticated;
!
@end

105. use ~iphone and ~ipad
if you’re developing a universal app add tilde to xib name instead of underscore
!
!

106. ~iphone and ~ipad
// MGAHomeViewController_iPhone.xib
// MGAHomeViewController_iPad.xib
!
@implementation MGAHomeViewController
!
- (id)init
{
NSString *nibName = @"MGAHomeViewController_iPhone";
if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad)
{
nibName = @"MGAHomeViewController_iPad";
}
return [super initWithNibName:nibName bundle:nil];
}
!
@end

107. ~iphone and ~ipad
// MGAHomeViewController_iPhone.xib
// MGAHomeViewController_iPad.xib
!
@implementation MGAHomeViewController
!
- (id)init
{
NSString *nibName = @"MGAHomeViewController_iPhone";
if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad)
{
nibName = @"MGAHomeViewController_iPad";
}
return [super initWithNibName:nibName bundle:nil];
}
!
@end
please stop doing that!

108. ~iphone and ~ipad
// MGAHomeViewController_iPhone.xib
// MGAHomeViewController_iPad.xib
!
@implementation MGAHomeViewController
!
- (id)init
{
NSString *nibName = @"MGAHomeViewController_iPhone";
if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad)
{
nibName = @"MGAHomeViewController_iPad";
}
return [super initWithNibName:nibName bundle:nil];
}
!
@end
// MGAHomeViewController~iphone.xib
// MGAHomeViewController~ipad.xib
!
@implementation MGAHomeViewController
!
!
!
!
!
// no custom init required
!
!
!
!
!
!
!
@end

109. use ~iphone and ~ipad

110. use ~iphone and ~ipad
‣ Adding ~iphone and ~ipad to xib file name, the
runtime will automatically infer the correct xib to load
(e.g. MGAHomeViewController~iphone.xib and
MGAHomeViewController~ipad.xib)

111. use ~iphone and ~ipad
‣ Adding ~iphone and ~ipad to xib file name, the
runtime will automatically infer the correct xib to load
(e.g. MGAHomeViewController~iphone.xib and
MGAHomeViewController~ipad.xib)
‣ note, it’s case sensitive so iPhone and iPad, with a
capital P, do not work

112. organize #import statements
it’s a good practice grouping and commenting #import statements

113. organize #import statements
!
#import <CoreData/CoreData.h>
!
#import "MGAMapViewController.h"
#import “MGAPictureView.h"
#import “NSString+MGAAdditions.h”
!
#import “MGAUser.h"
!
#import <CoreLocation/CoreLocation.h>
#import “NSDate+MGAAdditions.h”
!
#import “MGAOrderCell.h"
#import “MGACustomer.h"
#import "UIImage+MGAAdditions.h"
!
#import “MGAHomeViewController.h"
#import <UIKit/UIKit.h>
!
#import “MGAUserCell.h"

114. organize #import statements
!
#import <CoreData/CoreData.h>
!
#import "MGAMapViewController.h"
#import “MGAPictureView.h"
#import “NSString+MGAAdditions.h”
!
#import “MGAUser.h"
!
#import <CoreLocation/CoreLocation.h>
#import “NSDate+MGAAdditions.h”
!
#import “MGAOrderCell.h"
#import “MGACustomer.h"
#import "UIImage+MGAAdditions.h"
!
#import “MGAHomeViewController.h"
#import <UIKit/UIKit.h>
!
#import “MGAUserCell.h"
!
// Frameworks
#import <UIKit/UIKit.h>
#import <CoreData/CoreData.h>
#import <CoreLocation/CoreLocation.h>
!
// View Controllers
#import "MGAMapViewController.h"
#import “MGAHomeViewController.h”
!
// Views
#import “MGAPictureView.h”
!
// Cells
#import “MGAUserCell.h”
#import “MGAOrderCell.h”
!
// Models
#import “MGAUser.h"
#import “MGACustomer.h”
!
// Categories
#import “NSDate+MGAAdditions.h”
#import “UIImage+MGAAdditions.h"
#import “NSString+MGAAdditions.h”

115. organize #import statements

116. organize #import statements
‣ group #imports

117. organize #import statements
‣ group #imports
‣ comment the groups

118. organize #import statements
‣ group #imports
‣ comment the groups
‣ If your are pedantic you can sort #import by length :)

119. use #pragma mark
organize your code, visually

120. #pragma mark
#pragma mark - View
!
- (void)viewDidLoad
{
[super viewDidLoad];
…
}
!
- (void)viewWillAppear:(BOOL)animated
{
[super viewWillAppear:animated];
…
}
!
#pragma mark - UIScrollViewDelegate
!
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
…
}
!
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
…
}
!
#pragma mark - Actions
!
- (IBAction)loginButtonTouched:(id)sender
{
}

121. #pragma mark

122. #pragma mark

123. #pragma mark
‣ Use #pragma mark in your @implementation to divide
code into logical sections

124. #pragma mark
‣ Use #pragma mark in your @implementation to divide
code into logical sections
‣ It is also a way to organize your methods in the
method list pop up view in Xcode

125. Coding

126. don’t #import in header file
most #import statements should only be written in .m files, not .h headers

127. don’t #import in header file
#import "MGAUser.h"
#import "MGANetworkManager.h"
!
@interface MGALoginViewController : UIViewController
!
@property (nonatomic, readonly) MGAUser *user;
@property (nonatomic, strong, readwrite) MGANetworkManager *network;
!
@end
!
!
!
!
// MGALoginViewController.m
!
@implementation MGALoginViewController
!
!
@end

128. don’t #import in header file
#import "MGAUser.h"
#import "MGANetworkManager.h"
!
@interface MGALoginViewController : UIViewController
!
@property (nonatomic, readonly) MGAUser *user;
@property (nonatomic, strong, readwrite) MGANetworkManager *network;
!
@end
!
!
!
!
// MGALoginViewController.m
!
@implementation MGALoginViewController
!
!
@end
@class MGAUser; // forward class declaration
@class MGANetworkManager; // forward class declaration
!
@interface MGALoginViewController : UIViewController
!
@property (nonatomic, readonly) MGAUser *user;
@property (nonatomic, strong, readwrite) MGANetworkManager *network;
!
@end
!
!
!
!
// MGALoginViewController.m
!
#import "MGAUser.h"
#import “MGANetworkManager.h"
!
@implementation MGALoginViewController
!
!
@end

129. don’t #import in header file

130. don’t #import in header file
‣ Rather than adding #import statements for each class,
it's good practice to use forward class declarations in
the header, and import them in the implementation

131. don’t #import in header file
‣ Rather than adding #import statements for each class,
it's good practice to use forward class declarations in
the header, and import them in the implementation
‣ It reduce compile times and cyclical references

132. don’t #import in header file
‣ Rather than adding #import statements for each class,
it's good practice to use forward class declarations in
the header, and import them in the implementation
‣ It reduce compile times and cyclical references
‣ The one real exception is when subclassing another
custom class, you'll need to #import its header.

133. use typedef to simplify Block syntax
If you need to define more than one block with the same signature, you might like to
define your own type for that signature

134. blocks with typedef

135. blocks with typedef
!
!
!
@interface MGACustomer
!
!
!
- (void)createOrder:(void(^)(MGAOrder *order))completion;
!
@end

136. blocks with typedef
!
!
!
@interface MGACustomer
!
!
!
- (void)createOrder:(void(^)(MGAOrder *order))completion;
!
@end
typedef void(^MGACustomerBlock)(MGAOrder *order);
!
!
@interface MGACustomer
!
!
!
- (void)createOrder:(void(^)(MGAOrder *order))completion;
!
@end

137. blocks with typedef
!
!
!
@interface MGACustomer
!
!
!
- (void)createOrder:(void(^)(MGAOrder *order))completion;
!
@end
typedef void(^MGACustomerBlock)(MGAOrder *order);
!
!
@interface MGACustomer
!
!
!
- (void)createOrder:(void(^)(MGAOrder *order))completion;
!
@end
typedef void(^MGACustomerBlock)(MGAOrder *order);
!
!
@interface MGACustomer
!
!
!
- (void)createOrder:(MGACustomerBlock)completion;
!
@end

138. blocks with typedef
!
!
!
@interface MGACustomer
!
!
!
- (void)createOrder:(void(^)(MGAOrder *order))completion;
!
@end
typedef void(^MGACustomerBlock)(MGAOrder *order);
!
!
@interface MGACustomer
!
!
!
- (void)createOrder:(void(^)(MGAOrder *order))completion;
!
@end
typedef void(^MGACustomerBlock)(MGAOrder *order);
!
!
@interface MGACustomer
!
!
!
- (void)createOrder:(MGACustomerBlock)completion;
!
@end
typedef void(^MGACustomerBlock)(MGAOrder *order);
!
!
@interface MGACustomer
!
@property (nonatomic, copy) MGACustomerBlock completionBlock;
!
- (void)createOrder:(MGACustomerBlock)completion;
!
@end

139. create types for blocks

140. create types for blocks
‣ types improve readability and clean up your method
definitions, life will be easier and It’s highly
recommend making use of them as much as possible

141. create types for blocks
‣ types improve readability and clean up your method
definitions, life will be easier and It’s highly
recommend making use of them as much as possible
‣ If you have to change the block signature, it is much
easier to change the typedef. The compiler, being a
nice fellow, will then tell you all the places the block
signature doesn’t match

142. how to access ivars
Oh my!

143. how to access ivars
!
- (instancetype)initWithUser:(MGAUser *)user
{
self = [super init];
if (self)
{
_user = user;
}
return self;
}
!
- (void)viewDidLoad
{
[super viewDidLoad];
[self.usernameLabel setText:self.user.name];
}
!
- (void)createNewUser
{
self.usernameLabel = [THMUser alloc] init];
}

144. how to access ivars

145. how to access ivars
‣ Direct access bypasses the property’s memory-
management semantics defined by the setter

146. how to access ivars
‣ Direct access bypasses the property’s memory-
management semantics defined by the setter
‣ KVO notifications would not be fired when accessing
the instance variables directly

147. how to access ivars
‣ Direct access bypasses the property’s memory-
management semantics defined by the setter
‣ KVO notifications would not be fired when accessing
the instance variables directly
‣ In init methods you should use direct instance variable
access, because subclasses could override the setter

148. how to access ivars
‣ Direct access bypasses the property’s memory-
management semantics defined by the setter
‣ KVO notifications would not be fired when accessing
the instance variables directly
‣ In init methods you should use direct instance variable
access, because subclasses could override the setter
‣ On the other part of class read/write data through
properties

149. always declare atomic/nonatomic
Properties are declared as atomic by default

150. declare atomic/nonatomic
#import <UIKit/UIKit.h>
!
@interface MGAMapViewController : UIViewController
!
@property (readonly) CERUser *user;
@property (copy) NSArray *locations;
@property (weak) IBOutlet UITableView *tableView;
!
@end

151. declare atomic/nonatomic
#import <UIKit/UIKit.h>
!
@interface MGAMapViewController : UIViewController
!
@property (readonly) CERUser *user;
@property (copy) NSArray *locations;
@property (weak) IBOutlet UITableView *tableView;
!
@end
#import <UIKit/UIKit.h>
!
@interface MGAMapViewController : UIViewController
!
@property (nonatomic, readonly) CERUser *user;
@property (nonatomic, copy) NSArray *locations;
@property (nonatomic, weak) IBOutlet UITableView *tableView;
!
@end

152. declare atomic/nonatomic
#import <UIKit/UIKit.h>
!
@interface MGAMapViewController : UIViewController
!
@property (readonly) CERUser *user;
@property (copy) NSArray *locations;
@property (weak) IBOutlet UITableView *tableView;
!
@end
#import <UIKit/UIKit.h>
!
@interface MGAMapViewController : UIViewController
!
@property (nonatomic, readonly) CERUser *user;
@property (nonatomic, copy) NSArray *locations;
@property (nonatomic, weak) IBOutlet UITableView *tableView;
!
@end
#import <UIKit/UIKit.h>
!
@interface MGAMapViewController : UIViewController
!
@property (nonatomic, readonly) CERUser *user;
@property (nonatomic, readwrite, copy) NSArray *locations;
@property (nonatomic, readwrite, weak) IBOutlet UITableView *tableView;
!
@end

153. declare atomic/nonatomic

154. declare atomic/nonatomic
‣ By default, synthesized accessors include locking to
make them atomic

155. declare atomic/nonatomic
‣ By default, synthesized accessors include locking to
make them atomic
‣ If you not need locking on property use nonatomic on
iOS, since performance is severely impacted if atomic
is used

156. use read-only properties
read-only properties are great for exposing information, you should use them often

157. read-only properties
!
@interface MGAMapViewController : UIViewController
!
@property (nonatomic, readonly) MGAUser *user;
@property (nonatomic, readonly) NSArray *locations;
!
@end

158. read-only properties
!
@interface MGAMapViewController : UIViewController
!
@property (nonatomic, readonly) MGAUser *user;
@property (nonatomic, readonly) NSArray *locations;
!
@end
!
@interface MGAMapViewController : UIViewController
!
@property (nonatomic, readonly) MGAUser *user;
@property (nonatomic, readonly) NSArray *locations;
!
@end
!
!
!
!
!
!
!
!
!
!
@implementation MGAMapViewController
!
- (instancetype)initWithUser:(MGaUser *)user
{
self = [super init];
if (self) {
_user = user;
}
return self;
}
!
@end

159. read-only properties
!
@interface MGAMapViewController : UIViewController
!
@property (nonatomic, readonly) MGAUser *user;
@property (nonatomic, readonly) NSArray *locations;
!
@end
!
@interface MGAMapViewController : UIViewController
!
@property (nonatomic, readonly) MGAUser *user;
@property (nonatomic, readonly) NSArray *locations;
!
@end
!
!
!
!
!
!
!
!
!
!
@implementation MGAMapViewController
!
- (instancetype)initWithUser:(MGaUser *)user
{
self = [super init];
if (self) {
_user = user;
}
return self;
}
!
@end
!
@interface MGAMapViewController : UIViewController
!
@property (nonatomic, readonly) MGAUser *user;
@property (nonatomic, readonly) NSArray *locations;
!
@end
!
!
@interface MGAMapViewController ()
!
@property (nonatomic, strong, readwrite) MGAUser *user;
@property (nonatomic, strong, readwrite) NSArray *locations;
!
@end
!
!
@implementation MGAMapViewController
!
- (instancetype)initWithUser:(MGAUser *)user
{
self = [super init];
if (self) {
_user = user;
}
return self;
}
!
@end

160. use read-only properties

161. use read-only properties
‣ expose object data with read-only properties, unless
you really need to allow access to internal data
through a public setter

162. use read-only properties
‣ expose object data with read-only properties, unless
you really need to allow access to internal data
through a public setter
‣ for read-only properties, you should defined a public
getter but a private setter in class extension

163. use weak to avoid retain cycles
a wrong memory management involves in memory leaks

164. retain cycle

165. retain cycle
Object BObject A

166. retain cycle
Object B
@property (strong)
Object A

167. retain cycle
Object B
@property (strong)
@property (strong)
Object A

168. retain cycle
Object B
@property (strong)
@property (strong)
Object A

169. retain cycle
Object B
@property (strong)
@property (strong)
Object A

170. retain cycle
Object B
@property (strong)
Object A
@property (weak)

171. use __weak typeof
a wrong memory management involves in memory leaks

172. use __weak typeof

173. use __weak typeof
- (void)viewDidLoad
{
[super viewDidLoad];
self.manager = [[MGANetworkManager alloc] init];
!
!
!
[self.manager getUsers:^(NSArray *users, NSError *error)
{
if (!error)
{
self.users = elements;
[self.usersTableView reloadData];
}
}];
}

174. use __weak typeof
- (void)viewDidLoad
{
[super viewDidLoad];
self.manager = [[MGANetworkManager alloc] init];
!
!
!
[self.manager getUsers:^(NSArray *users, NSError *error)
{
if (!error)
{
self.users = elements;
[self.usersTableView reloadData];
}
}];
}

175. use __weak typeof
- (void)viewDidLoad
{
[super viewDidLoad];
self.manager = [[MGANetworkManager alloc] init];
!
!
!
[self.manager getUsers:^(NSArray *users, NSError *error)
{
if (!error)
{
self.users = elements;
[self.usersTableView reloadData];
}
}];
}

176. use __weak typeof
- (void)viewDidLoad
{
[super viewDidLoad];
self.manager = [[MGANetworkManager alloc] init];
!
!
!
[self.manager getUsers:^(NSArray *users, NSError *error)
{
if (!error)
{
self.users = elements;
[self.usersTableView reloadData];
}
}];
}
- (void)viewDidLoad
{
[super viewDidLoad];
self.manager = [[MGANetworkManager alloc] init];
!
__weak THMReportsViewController weakSelf = self;
!
[weakSelf.manager getUsers:^(NSArray *users, NSError *error)
{
if (!error)
{
weakSelf.users = elements;
[weakSelf.usersTableView reloadData];
}
}];
}

177. use __weak typeof
- (void)viewDidLoad
{
[super viewDidLoad];
self.manager = [[MGANetworkManager alloc] init];
!
!
!
[self.manager getUsers:^(NSArray *users, NSError *error)
{
if (!error)
{
self.users = elements;
[self.usersTableView reloadData];
}
}];
}
- (void)viewDidLoad
{
[super viewDidLoad];
self.manager = [[MGANetworkManager alloc] init];
!
__weak THMReportsViewController weakSelf = self;
!
[weakSelf.manager getUsers:^(NSArray *users, NSError *error)
{
if (!error)
{
weakSelf.users = elements;
[weakSelf.usersTableView reloadData];
}
}];
}
- (void)viewDidLoad
{
[super viewDidLoad];
self.manager = [[MGANetworkManager alloc] init];
!
__weak typeof(self) weakSelf = self;
!
[weakSelf.manager getUsers:^(NSArray *users, NSError *error)
{
if (!error)
{
weakSelf.users = elements;
[weakSelf.usersTableView reloadData];
}
}];
}

178. Manage third-part libraries with CocoaPods
it’s an application level dependency manager for the Objective-C projects

179. Cocoapods

180. Cocoapods
$ sudo gem install cocoapods
$ cd MyGreatApp
$ pod init
$ edit Podfile

181. Cocoapods
$ sudo gem install cocoapods
$ cd MyGreatApp
$ pod init
$ edit Podfile
platform :ios, '6.1'
pod 'RestKit', '~> 0.22.0'
pod 'FXKeychain', '~> 1.5'
pod 'SDWebImage', '~> 3.5.2'
pod 'SDWebImage-ProgressView', '~> 0.3.0'
pod 'RHAddressBook', '~> 1.1.1'
pod 'FormatterKit', '~> 1.4.2'

182. Cocoapods
$ sudo gem install cocoapods
$ cd MyGreatApp
$ pod init
$ edit Podfile
platform :ios, '6.1'
pod 'RestKit', '~> 0.22.0'
pod 'FXKeychain', '~> 1.5'
pod 'SDWebImage', '~> 3.5.2'
pod 'SDWebImage-ProgressView', '~> 0.3.0'
pod 'RHAddressBook', '~> 1.1.1'
pod 'FormatterKit', '~> 1.4.2'
$ pod install

183. Cocoapods
$ sudo gem install cocoapods
$ cd MyGreatApp
$ pod init
$ edit Podfile
platform :ios, '6.1'
pod 'RestKit', '~> 0.22.0'
pod 'FXKeychain', '~> 1.5'
pod 'SDWebImage', '~> 3.5.2'
pod 'SDWebImage-ProgressView', '~> 0.3.0'
pod 'RHAddressBook', '~> 1.1.1'
pod 'FormatterKit', '~> 1.4.2'
$ pod install

184. Cocoapods
$ sudo gem install cocoapods
$ cd MyGreatApp
$ pod init
$ edit Podfile
platform :ios, '6.1'
pod 'RestKit', '~> 0.22.0'
pod 'FXKeychain', '~> 1.5'
pod 'SDWebImage', '~> 3.5.2'
pod 'SDWebImage-ProgressView', '~> 0.3.0'
pod 'RHAddressBook', '~> 1.1.1'
pod 'FormatterKit', '~> 1.4.2'
$ pod install

185. Cocoapods
$ sudo gem install cocoapods
$ cd MyGreatApp
$ pod init
$ edit Podfile
platform :ios, '6.1'
pod 'RestKit', '~> 0.22.0'
pod 'FXKeychain', '~> 1.5'
pod 'SDWebImage', '~> 3.5.2'
pod 'SDWebImage-ProgressView', '~> 0.3.0'
pod 'RHAddressBook', '~> 1.1.1'
pod 'FormatterKit', '~> 1.4.2'
$ pod install
Analyzing dependencies

186. Cocoapods
$ sudo gem install cocoapods
$ cd MyGreatApp
$ pod init
$ edit Podfile
platform :ios, '6.1'
pod 'RestKit', '~> 0.22.0'
pod 'FXKeychain', '~> 1.5'
pod 'SDWebImage', '~> 3.5.2'
pod 'SDWebImage-ProgressView', '~> 0.3.0'
pod 'RHAddressBook', '~> 1.1.1'
pod 'FormatterKit', '~> 1.4.2'
$ pod install
Analyzing dependencies

187. Cocoapods
$ sudo gem install cocoapods
$ cd MyGreatApp
$ pod init
$ edit Podfile
platform :ios, '6.1'
pod 'RestKit', '~> 0.22.0'
pod 'FXKeychain', '~> 1.5'
pod 'SDWebImage', '~> 3.5.2'
pod 'SDWebImage-ProgressView', '~> 0.3.0'
pod 'RHAddressBook', '~> 1.1.1'
pod 'FormatterKit', '~> 1.4.2'
$ pod install
Analyzing dependencies
Downloading dependencies

188. Cocoapods
$ sudo gem install cocoapods
$ cd MyGreatApp
$ pod init
$ edit Podfile
platform :ios, '6.1'
pod 'RestKit', '~> 0.22.0'
pod 'FXKeychain', '~> 1.5'
pod 'SDWebImage', '~> 3.5.2'
pod 'SDWebImage-ProgressView', '~> 0.3.0'
pod 'RHAddressBook', '~> 1.1.1'
pod 'FormatterKit', '~> 1.4.2'
$ pod install
Analyzing dependencies
Downloading dependencies
Using AFNetworking (1.3.3)

189. Cocoapods
$ sudo gem install cocoapods
$ cd MyGreatApp
$ pod init
$ edit Podfile
platform :ios, '6.1'
pod 'RestKit', '~> 0.22.0'
pod 'FXKeychain', '~> 1.5'
pod 'SDWebImage', '~> 3.5.2'
pod 'SDWebImage-ProgressView', '~> 0.3.0'
pod 'RHAddressBook', '~> 1.1.1'
pod 'FormatterKit', '~> 1.4.2'
$ pod install
Analyzing dependencies
Downloading dependencies
Using AFNetworking (1.3.3)
Using FXKeychain (1.5)

190. Cocoapods
$ sudo gem install cocoapods
$ cd MyGreatApp
$ pod init
$ edit Podfile
platform :ios, '6.1'
pod 'RestKit', '~> 0.22.0'
pod 'FXKeychain', '~> 1.5'
pod 'SDWebImage', '~> 3.5.2'
pod 'SDWebImage-ProgressView', '~> 0.3.0'
pod 'RHAddressBook', '~> 1.1.1'
pod 'FormatterKit', '~> 1.4.2'
$ pod install
Analyzing dependencies
Downloading dependencies
Using AFNetworking (1.3.3)
Using FXKeychain (1.5)
Using FormatterKit (1.4.2)

191. Cocoapods
$ sudo gem install cocoapods
$ cd MyGreatApp
$ pod init
$ edit Podfile
platform :ios, '6.1'
pod 'RestKit', '~> 0.22.0'
pod 'FXKeychain', '~> 1.5'
pod 'SDWebImage', '~> 3.5.2'
pod 'SDWebImage-ProgressView', '~> 0.3.0'
pod 'RHAddressBook', '~> 1.1.1'
pod 'FormatterKit', '~> 1.4.2'
$ pod install
Analyzing dependencies
Downloading dependencies
Using AFNetworking (1.3.3)
Using FXKeychain (1.5)
Using FormatterKit (1.4.2)
Using ISO8601DateFormatterValueTransformer (0.5.0)

192. Cocoapods
$ sudo gem install cocoapods
$ cd MyGreatApp
$ pod init
$ edit Podfile
platform :ios, '6.1'
pod 'RestKit', '~> 0.22.0'
pod 'FXKeychain', '~> 1.5'
pod 'SDWebImage', '~> 3.5.2'
pod 'SDWebImage-ProgressView', '~> 0.3.0'
pod 'RHAddressBook', '~> 1.1.1'
pod 'FormatterKit', '~> 1.4.2'
$ pod install
Analyzing dependencies
Downloading dependencies
Using AFNetworking (1.3.3)
Using FXKeychain (1.5)
Using FormatterKit (1.4.2)
Using ISO8601DateFormatterValueTransformer (0.5.0)
Using RHAddressBook (1.1.1)

193. Cocoapods
$ sudo gem install cocoapods
$ cd MyGreatApp
$ pod init
$ edit Podfile
platform :ios, '6.1'
pod 'RestKit', '~> 0.22.0'
pod 'FXKeychain', '~> 1.5'
pod 'SDWebImage', '~> 3.5.2'
pod 'SDWebImage-ProgressView', '~> 0.3.0'
pod 'RHAddressBook', '~> 1.1.1'
pod 'FormatterKit', '~> 1.4.2'
$ pod install
Analyzing dependencies
Downloading dependencies
Using AFNetworking (1.3.3)
Using FXKeychain (1.5)
Using FormatterKit (1.4.2)
Using ISO8601DateFormatterValueTransformer (0.5.0)
Using RHAddressBook (1.1.1)
Using RKValueTransformers (1.0.1)

194. Cocoapods
$ sudo gem install cocoapods
$ cd MyGreatApp
$ pod init
$ edit Podfile
platform :ios, '6.1'
pod 'RestKit', '~> 0.22.0'
pod 'FXKeychain', '~> 1.5'
pod 'SDWebImage', '~> 3.5.2'
pod 'SDWebImage-ProgressView', '~> 0.3.0'
pod 'RHAddressBook', '~> 1.1.1'
pod 'FormatterKit', '~> 1.4.2'
$ pod install
Analyzing dependencies
Downloading dependencies
Using AFNetworking (1.3.3)
Using FXKeychain (1.5)
Using FormatterKit (1.4.2)
Using ISO8601DateFormatterValueTransformer (0.5.0)
Using RHAddressBook (1.1.1)
Using RKValueTransformers (1.0.1)
Using RestKit (0.22.0)

195. Cocoapods
$ sudo gem install cocoapods
$ cd MyGreatApp
$ pod init
$ edit Podfile
platform :ios, '6.1'
pod 'RestKit', '~> 0.22.0'
pod 'FXKeychain', '~> 1.5'
pod 'SDWebImage', '~> 3.5.2'
pod 'SDWebImage-ProgressView', '~> 0.3.0'
pod 'RHAddressBook', '~> 1.1.1'
pod 'FormatterKit', '~> 1.4.2'
$ pod install
Analyzing dependencies
Downloading dependencies
Using AFNetworking (1.3.3)
Using FXKeychain (1.5)
Using FormatterKit (1.4.2)
Using ISO8601DateFormatterValueTransformer (0.5.0)
Using RHAddressBook (1.1.1)
Using RKValueTransformers (1.0.1)
Using RestKit (0.22.0)
Using SDWebImage (3.5.4)

196. Cocoapods
$ sudo gem install cocoapods
$ cd MyGreatApp
$ pod init
$ edit Podfile
platform :ios, '6.1'
pod 'RestKit', '~> 0.22.0'
pod 'FXKeychain', '~> 1.5'
pod 'SDWebImage', '~> 3.5.2'
pod 'SDWebImage-ProgressView', '~> 0.3.0'
pod 'RHAddressBook', '~> 1.1.1'
pod 'FormatterKit', '~> 1.4.2'
$ pod install
Analyzing dependencies
Downloading dependencies
Using AFNetworking (1.3.3)
Using FXKeychain (1.5)
Using FormatterKit (1.4.2)
Using ISO8601DateFormatterValueTransformer (0.5.0)
Using RHAddressBook (1.1.1)
Using RKValueTransformers (1.0.1)
Using RestKit (0.22.0)
Using SDWebImage (3.5.4)
Using SDWebImage-ProgressView (0.3.1)

197. Cocoapods
$ sudo gem install cocoapods
$ cd MyGreatApp
$ pod init
$ edit Podfile
platform :ios, '6.1'
pod 'RestKit', '~> 0.22.0'
pod 'FXKeychain', '~> 1.5'
pod 'SDWebImage', '~> 3.5.2'
pod 'SDWebImage-ProgressView', '~> 0.3.0'
pod 'RHAddressBook', '~> 1.1.1'
pod 'FormatterKit', '~> 1.4.2'
$ pod install
Analyzing dependencies
Downloading dependencies
Using AFNetworking (1.3.3)
Using FXKeychain (1.5)
Using FormatterKit (1.4.2)
Using ISO8601DateFormatterValueTransformer (0.5.0)
Using RHAddressBook (1.1.1)
Using RKValueTransformers (1.0.1)
Using RestKit (0.22.0)
Using SDWebImage (3.5.4)
Using SDWebImage-ProgressView (0.3.1)
Using SOCKit (1.1)

198. Cocoapods
$ sudo gem install cocoapods
$ cd MyGreatApp
$ pod init
$ edit Podfile
platform :ios, '6.1'
pod 'RestKit', '~> 0.22.0'
pod 'FXKeychain', '~> 1.5'
pod 'SDWebImage', '~> 3.5.2'
pod 'SDWebImage-ProgressView', '~> 0.3.0'
pod 'RHAddressBook', '~> 1.1.1'
pod 'FormatterKit', '~> 1.4.2'
$ pod install
Analyzing dependencies
Downloading dependencies
Using AFNetworking (1.3.3)
Using FXKeychain (1.5)
Using FormatterKit (1.4.2)
Using ISO8601DateFormatterValueTransformer (0.5.0)
Using RHAddressBook (1.1.1)
Using RKValueTransformers (1.0.1)
Using RestKit (0.22.0)
Using SDWebImage (3.5.4)
Using SDWebImage-ProgressView (0.3.1)
Using SOCKit (1.1)
Using TransitionKit (2.0.0)

199. Cocoapods
$ sudo gem install cocoapods
$ cd MyGreatApp
$ pod init
$ edit Podfile
platform :ios, '6.1'
pod 'RestKit', '~> 0.22.0'
pod 'FXKeychain', '~> 1.5'
pod 'SDWebImage', '~> 3.5.2'
pod 'SDWebImage-ProgressView', '~> 0.3.0'
pod 'RHAddressBook', '~> 1.1.1'
pod 'FormatterKit', '~> 1.4.2'
$ pod install
Analyzing dependencies
Downloading dependencies
Using AFNetworking (1.3.3)
Using FXKeychain (1.5)
Using FormatterKit (1.4.2)
Using ISO8601DateFormatterValueTransformer (0.5.0)
Using RHAddressBook (1.1.1)
Using RKValueTransformers (1.0.1)
Using RestKit (0.22.0)
Using SDWebImage (3.5.4)
Using SDWebImage-ProgressView (0.3.1)
Using SOCKit (1.1)
Using TransitionKit (2.0.0)
Generating Pods project

200. Cocoapods
$ sudo gem install cocoapods
$ cd MyGreatApp
$ pod init
$ edit Podfile
platform :ios, '6.1'
pod 'RestKit', '~> 0.22.0'
pod 'FXKeychain', '~> 1.5'
pod 'SDWebImage', '~> 3.5.2'
pod 'SDWebImage-ProgressView', '~> 0.3.0'
pod 'RHAddressBook', '~> 1.1.1'
pod 'FormatterKit', '~> 1.4.2'
$ pod install
Analyzing dependencies
Downloading dependencies
Using AFNetworking (1.3.3)
Using FXKeychain (1.5)
Using FormatterKit (1.4.2)
Using ISO8601DateFormatterValueTransformer (0.5.0)
Using RHAddressBook (1.1.1)
Using RKValueTransformers (1.0.1)
Using RestKit (0.22.0)
Using SDWebImage (3.5.4)
Using SDWebImage-ProgressView (0.3.1)
Using SOCKit (1.1)
Using TransitionKit (2.0.0)
Generating Pods project
Integrating client project

201. Cocoapods
$ sudo gem install cocoapods
$ cd MyGreatApp
$ pod init
$ edit Podfile
platform :ios, '6.1'
pod 'RestKit', '~> 0.22.0'
pod 'FXKeychain', '~> 1.5'
pod 'SDWebImage', '~> 3.5.2'
pod 'SDWebImage-ProgressView', '~> 0.3.0'
pod 'RHAddressBook', '~> 1.1.1'
pod 'FormatterKit', '~> 1.4.2'
$ pod install
Analyzing dependencies
Downloading dependencies
Using AFNetworking (1.3.3)
Using FXKeychain (1.5)
Using FormatterKit (1.4.2)
Using ISO8601DateFormatterValueTransformer (0.5.0)
Using RHAddressBook (1.1.1)
Using RKValueTransformers (1.0.1)
Using RestKit (0.22.0)
Using SDWebImage (3.5.4)
Using SDWebImage-ProgressView (0.3.1)
Using SOCKit (1.1)
Using TransitionKit (2.0.0)
Generating Pods project
Integrating client project

202. Cocoapods
$ sudo gem install cocoapods
$ cd MyGreatApp
$ pod init
$ edit Podfile
platform :ios, '6.1'
pod 'RestKit', '~> 0.22.0'
pod 'FXKeychain', '~> 1.5'
pod 'SDWebImage', '~> 3.5.2'
pod 'SDWebImage-ProgressView', '~> 0.3.0'
pod 'RHAddressBook', '~> 1.1.1'
pod 'FormatterKit', '~> 1.4.2'
$ pod install
Analyzing dependencies
Downloading dependencies
Using AFNetworking (1.3.3)
Using FXKeychain (1.5)
Using FormatterKit (1.4.2)
Using ISO8601DateFormatterValueTransformer (0.5.0)
Using RHAddressBook (1.1.1)
Using RKValueTransformers (1.0.1)
Using RestKit (0.22.0)
Using SDWebImage (3.5.4)
Using SDWebImage-ProgressView (0.3.1)
Using SOCKit (1.1)
Using TransitionKit (2.0.0)
Generating Pods project
Integrating client project
$

203. Cocoapods

204. Cocoapods
‣ CocoaPods manage dependency for you, it download
source files, imports headers and configures flags

205. Cocoapods
‣ CocoaPods manage dependency for you, it download
source files, imports headers and configures flags
‣ CocoaPods is strongly inspired by a combination of
the Ruby projects RubyGems and Bundler

206. Cocoapods
‣ CocoaPods manage dependency for you, it download
source files, imports headers and configures flags
‣ CocoaPods is strongly inspired by a combination of
the Ruby projects RubyGems and Bundler
‣ CocoaPods focuses on source-based distribution of
third party code and automatic integration into Xcode
projects

207. Cocoapods
‣ CocoaPods manage dependency for you, it download
source files, imports headers and configures flags
‣ CocoaPods is strongly inspired by a combination of
the Ruby projects RubyGems and Bundler
‣ CocoaPods focuses on source-based distribution of
third party code and automatic integration into Xcode
projects
‣ CocoaPods runs from the command line

208. Framework

209. Key-Value Coding
dynamically set and get properties and object graph

210. Key-Value Coding
MGACustomer *c1 = [[MGACustomer alloc] initWithName:@“ACME Inc.”];
c1.address = [[MGAAddress alloc] initWithZip:@“33568”];
!
!
[c1 valueForKey:@"name"]; // ACME Inc.
[c1 valueForKeyPath:@“address.zip"]; // 33568

211. Key-Value Coding
MGACustomer *c1 = [[MGACustomer alloc] initWithName:@“ACME Inc.”];
c1.address = [[MGAAddress alloc] initWithZip:@“33568”];
!
!
[c1 valueForKey:@"name"]; // ACME Inc.
[c1 valueForKeyPath:@“address.zip"]; // 33568
NSArray *names = @[ @"Steve", @"Bill", @"Ive" ];
!
// you can “get the value” of any method with no parameter
[names valueForKey:@"uppercaseString"]; // @[ @“STEVE”, @“BILL”, @“IVE”]
[names valueForKey:@"lowercaseString"]; // @[ @“steve”, @“bill”, @“ive”]
!
!
// It’s really any method.
// For example, -[NSObject self] is a method like any other.
[@"Steve" valueForKey:@“self"]; // @“Steve”
!
!
// KVC automatically boxes and unboxes values
[names valueForKey:@"length"]; // @[ @5, @4, @3 ]

212. Key-Value Coding

213. Key-Value Coding
‣ Key-value coding is a mechanism for accessing an
object’s properties indirectly, using strings to identify
properties

214. Key-Value Coding
‣ Key-value coding is a mechanism for accessing an
object’s properties indirectly, using strings to identify
properties
‣ You can get the value of any method with no
parameter

215. Key-Value Coding
‣ Key-value coding is a mechanism for accessing an
object’s properties indirectly, using strings to identify
properties
‣ You can get the value of any method with no
parameter
‣ Key-Value Coding automatically boxes and unboxes
values into their object representation.

216. discover KVC Collection Operators
save a few extra lines of code

217. KVC Collection Operators

218. KVC Collection Operators
MGAPerson *p1 = [[MGAPerson alloc] initWithName:@"Max" age:34];
MGAPerson *p2 = [[MGAPerson alloc] initWithName:@"Steve" age:54];
MGAPerson *p3 = [[MGAPerson alloc] initWithName:@"Bill" age:62];
NSArray *people = @[ p1, p2, p3 ];
// Simple Collection Operators
[people valueForKeyPath:@"@count"]; // 3
[people valueForKeyPath:@"@sum.age"]; // 150.00
[people valueForKeyPath:@"@avg.age"]; // 50.00
[people valueForKeyPath:@"@max.age"]; // 63.00
// Objects Operators
[people valueForKeyPath:@"@unionOfObjects.name"]; // "Max", "Steve", “Bill"
// Simple Collection Operators with NSNumber
NSArray *numbers = @[ @(1), @(2), @(3) ];
[numbers valueForKeyPath:@"@max.self"]; // 3

219. KVC Collection Operators

220. KVC Collection Operators
‣ Collection operators allow actions to be performed on
the items of a collection using key path notation and
an action operator

221. KVC Collection Operators
‣ Collection operators allow actions to be performed on
the items of a collection using key path notation and
an action operator
‣ Collection operators are specialized key paths that are
passed as the parameter to the valueForKeyPath:
method

222. KVC Collection Operators
‣ Collection operators allow actions to be performed on
the items of a collection using key path notation and
an action operator
‣ Collection operators are specialized key paths that are
passed as the parameter to the valueForKeyPath:
method
‣ The operator is specified by a string preceded by an at
sign (@)

223. discover NSBlockOperation class

224. NSBlockOperation

225. NSBlockOperation
NSBlockOperation *blockOp = [[NSBlockOperation alloc] init];

226. NSBlockOperation
NSBlockOperation *blockOp = [[NSBlockOperation alloc] init];

227. NSBlockOperation
NSBlockOperation *blockOp = [[NSBlockOperation alloc] init];
__weak typeof(blockOp) weakOp = blockOp;

228. NSBlockOperation
NSBlockOperation *blockOp = [[NSBlockOperation alloc] init];
__weak typeof(blockOp) weakOp = blockOp;

229. NSBlockOperation
NSBlockOperation *blockOp = [[NSBlockOperation alloc] init];
__weak typeof(blockOp) weakOp = blockOp;
[blockOp addExecutionBlock:^

230. NSBlockOperation
NSBlockOperation *blockOp = [[NSBlockOperation alloc] init];
__weak typeof(blockOp) weakOp = blockOp;
[blockOp addExecutionBlock:^
{

231. NSBlockOperation
NSBlockOperation *blockOp = [[NSBlockOperation alloc] init];
__weak typeof(blockOp) weakOp = blockOp;
[blockOp addExecutionBlock:^
{
for (NSInteger i = 0; i < 10000; i++)

232. NSBlockOperation
NSBlockOperation *blockOp = [[NSBlockOperation alloc] init];
__weak typeof(blockOp) weakOp = blockOp;
[blockOp addExecutionBlock:^
{
for (NSInteger i = 0; i < 10000; i++)
{

233. NSBlockOperation
NSBlockOperation *blockOp = [[NSBlockOperation alloc] init];
__weak typeof(blockOp) weakOp = blockOp;
[blockOp addExecutionBlock:^
{
for (NSInteger i = 0; i < 10000; i++)
{
if ([weakOp isCancelled])

234. NSBlockOperation
NSBlockOperation *blockOp = [[NSBlockOperation alloc] init];
__weak typeof(blockOp) weakOp = blockOp;
[blockOp addExecutionBlock:^
{
for (NSInteger i = 0; i < 10000; i++)
{
if ([weakOp isCancelled])
{

235. NSBlockOperation
NSBlockOperation *blockOp = [[NSBlockOperation alloc] init];
__weak typeof(blockOp) weakOp = blockOp;
[blockOp addExecutionBlock:^
{
for (NSInteger i = 0; i < 10000; i++)
{
if ([weakOp isCancelled])
{
break;

236. NSBlockOperation
NSBlockOperation *blockOp = [[NSBlockOperation alloc] init];
__weak typeof(blockOp) weakOp = blockOp;
[blockOp addExecutionBlock:^
{
for (NSInteger i = 0; i < 10000; i++)
{
if ([weakOp isCancelled])
{
break;
}

237. NSBlockOperation
NSBlockOperation *blockOp = [[NSBlockOperation alloc] init];
__weak typeof(blockOp) weakOp = blockOp;
[blockOp addExecutionBlock:^
{
for (NSInteger i = 0; i < 10000; i++)
{
if ([weakOp isCancelled])
{
break;
}

238. NSBlockOperation
NSBlockOperation *blockOp = [[NSBlockOperation alloc] init];
__weak typeof(blockOp) weakOp = blockOp;
[blockOp addExecutionBlock:^
{
for (NSInteger i = 0; i < 10000; i++)
{
if ([weakOp isCancelled])
{
break;
}
NSLog(@"%i", i);

239. NSBlockOperation
NSBlockOperation *blockOp = [[NSBlockOperation alloc] init];
__weak typeof(blockOp) weakOp = blockOp;
[blockOp addExecutionBlock:^
{
for (NSInteger i = 0; i < 10000; i++)
{
if ([weakOp isCancelled])
{
break;
}
NSLog(@"%i", i);
}

240. NSBlockOperation
NSBlockOperation *blockOp = [[NSBlockOperation alloc] init];
__weak typeof(blockOp) weakOp = blockOp;
[blockOp addExecutionBlock:^
{
for (NSInteger i = 0; i < 10000; i++)
{
if ([weakOp isCancelled])
{
break;
}
NSLog(@"%i", i);
}
}];

241. NSBlockOperation
NSBlockOperation *blockOp = [[NSBlockOperation alloc] init];
__weak typeof(blockOp) weakOp = blockOp;
[blockOp addExecutionBlock:^
{
for (NSInteger i = 0; i < 10000; i++)
{
if ([weakOp isCancelled])
{
break;
}
NSLog(@"%i", i);
}
}];

242. NSBlockOperation
NSBlockOperation *blockOp = [[NSBlockOperation alloc] init];
__weak typeof(blockOp) weakOp = blockOp;
[blockOp addExecutionBlock:^
{
for (NSInteger i = 0; i < 10000; i++)
{
if ([weakOp isCancelled])
{
break;
}
NSLog(@"%i", i);
}
}];
[blockOp start];

243. NSBlockOperation

244. NSBlockOperation
‣ NSBlockOperation is a concrete subclass that wraps
block in operations

245. NSBlockOperation
‣ NSBlockOperation is a concrete subclass that wraps
block in operations
‣ You can use this object to execute several blocks at
once without having to create separate operation
objects for each

246. NSBlockOperation
‣ NSBlockOperation is a concrete subclass that wraps
block in operations
‣ You can use this object to execute several blocks at
once without having to create separate operation
objects for each
‣ When executing more than one block, the operation
itself is considered finished only when all blocks have
finished executing

247. NSError
it encapsulates richer and more extensible error information

248. Create an NSError

249. Create an NSError
NSString * const kMGAErrorDomain = @“com.acmeinc.MyGreatApp”;
typedef NS_ENUM(NSInteger, MGAErrorCode)
{
MGAErrorCodeUnableToLocateUser = 500,
MGAErrorCodeInvalidUser = 401
};
NSDictionary *userInfo =
@{
NSLocalizedDescriptionKey:
NSLocalizedString(@“Location error”, nil),
NSLocalizedFailureReasonErrorKey :
NSLocalizedString(@"The location service is not active.", nil),
NSLocalizedRecoverySuggestionErrorKey :
NSLocalizedString(@"Please turn on the location service and try again", nil)
};
NSError *error = [NSError errorWithDomain:kMGAErrorDomain
code:MGAErrorCodeUnableToLocateUser
userInfo:userInfo];

250. Handle NSError

251. Handle NSError
- (void)handleError:(NSError *)error
{
if (error)
{
NSString *errorMessage;
errorMessage = [NSString stringWithFormat:@"%@n%@",
error.localizedFailureReason,
error.localizedRecoverySuggestion];
UIAlertView *alert = [[UIAlertView alloc]
initWithTitle:error.localizedDescription
message:errorMessage
delegate:nil
cancelButtonTitle:NSLocalizedString(@"OK", nil)
otherButtonTitles:nil, nil];
[alert show];
}
}

252. Consuming NSError

253. Consuming NSError
- (void)doLogin
{
NSString *user = self.usernameTextField.text;
NSString *pass = self.passwordTextField.text;
__weak typeof(self) weakSelf = self;
[self.service loginWithUser:user pass:pass completion:^(TMGAUser *user, NSError *error)
{
[weakSelf handleError:error];
if (!error)
{
[weakSelf navigateToHome];
}
}];
}

254. NSError

255. NSError
‣ An NSError object encapsulates richer and more
extensible error information than is possible using
only an error code or error string

256. NSError
‣ An NSError object encapsulates richer and more
extensible error information than is possible using
only an error code or error string
‣ The core attributes of an NSError object are an error
domain, a domain-specific error code and a user info
dictionary containing application specific information.

257. NSError
‣ An NSError object encapsulates richer and more
extensible error information than is possible using
only an error code or error string
‣ The core attributes of an NSError object are an error
domain, a domain-specific error code and a user info
dictionary containing application specific information.
‣ Domain-specific error codes are generally defined by
constants in an enum.

258. use NSCache
It’s a collection-like container, or cache, that stores key-value pairs, similar to the
NSMutableDictionary class.

259. NSCache

260. NSCache
NSCache *cache = [[NSCache alloc] init];
!
!
// Sets the maximum number of objects that the cache can hold.
!
// This limit is not a strict limit, and if the cache goes over the limit,
// an object in the cache could be evicted instantly, later, or possibly never,
// all depending on the implementation details of the cache.
[cache setCountLimit:50];
!
!
// Sets the maximum total cost that the cache can have before it starts evicting objects
!
// If adding this object to the cache causes the cache’s total cost to rise above
// totalCostLimit, the cache could automatically evict some of its objects until its
// total cost falls below totalCostLimit. The order in which the cache evicts objects is
// not guaranteed. This limit is not a strict limit, and if the cache goes over the
// limit, an object in the cache could be evicted instantly, at a later point in time,
// or possibly never, all depending on the implementation details of the cache.
[cache setTotalCostLimit:5000];
!
!
// Add object to cache with cost
[cache setObject:customer1 forKey:@"c1" cost:10];
!
!
// Add object to cache without cost
[cache setObject:customer2 forKey:@"c2"];

261. NSCache

262. NSCache
‣ NSCache is basically just an NSMutableDictionary that
automatically evicts objects in order to free up space
in memory as needed

263. NSCache
‣ NSCache is basically just an NSMutableDictionary that
automatically evicts objects in order to free up space
in memory as needed
‣ The NSCache class incorporates various auto-removal
policies, which ensure that it does not use too much of
the system’s memory. The system automatically carries
out these policies if memory is needed by other
applications. When invoked, these policies remove
some items from the cache, minimizing its memory
footprint.

264. NSCache

265. NSCache
‣ It is guaranteed to be thread-safe.

266. NSCache
‣ It is guaranteed to be thread-safe.
‣ It is much slower to access.

267. NSCache
‣ It is guaranteed to be thread-safe.
‣ It is much slower to access.
‣ It may throw out objects from time to time. You can set
costs and limits, but they're not guaranteed to be followed.

268. NSCache
‣ It is guaranteed to be thread-safe.
‣ It is much slower to access.
‣ It may throw out objects from time to time. You can set
costs and limits, but they're not guaranteed to be followed.
‣ It is not toll-free bridged to anything in CoreFoundation.

269. NSCache
‣ It is guaranteed to be thread-safe.
‣ It is much slower to access.
‣ It may throw out objects from time to time. You can set
costs and limits, but they're not guaranteed to be followed.
‣ It is not toll-free bridged to anything in CoreFoundation.
‣ You can't query the number of objects that are in the
cache.

270. NSCache
‣ It is guaranteed to be thread-safe.
‣ It is much slower to access.
‣ It may throw out objects from time to time. You can set
costs and limits, but they're not guaranteed to be followed.
‣ It is not toll-free bridged to anything in CoreFoundation.
‣ You can't query the number of objects that are in the
cache.
‣ You can't enumerate a cache.

271. NSValue
NSValue is a simple container for a single C or Objective-C data value

272. NSValue

273. NSValue
NSMutableArray *items = [@[] mutableCopy];
[items addObject:[NSValue valueWithCGSize:CGSizeMake(200.0f, 300.0f)]];
NSValue *sizeValue = items[0];
CGSize size = [sizeValue CGSizeValue];
// define new struct
typedef struct MGAColor
{
float red, blue, green;
}
MGAColor;
MGAColor color = { 255.0, 0.0f, 34.0 };
[items addObject:[NSValue valueWithBytes:&color objCType:@encode(MGAColor)]];

274. NSValue
NSMutableArray *items = [@[] mutableCopy];
[items addObject:[NSValue valueWithCGSize:CGSizeMake(200.0f, 300.0f)]];
NSValue *sizeValue = items[0];
CGSize size = [sizeValue CGSizeValue];
// define new struct
typedef struct MGAColor
{
float red, blue, green;
}
MGAColor;
MGAColor color = { 255.0, 0.0f, 34.0 };
[items addObject:[NSValue valueWithBytes:&color objCType:@encode(MGAColor)]];
MGAUser *user = [[MGAUser alloc] init]; // it not conforms to <NSCopying>
NSMutableDictionary *items = [@{} mutableCopy];
// e.g. I want to store num of login attempts of a user
// because my custom class MGAUser does not conform to <NSCopying>
// I can’t use it as key value. The workaround is to box user instance
// into NSValue object with valueWithNonretainedObject:
[items setObject:numLogin forKey:[NSValue valueWithNonretainedObject:user]];

275. NSValue

276. NSValue
‣ It can hold scalars and value types, as well as pointers
and object IDs.

277. NSValue
‣ It can hold scalars and value types, as well as pointers
and object IDs.
‣ NSValue uses type encoding to create the necessary
data structures to represent values internally

278. NSValue
‣ It can hold scalars and value types, as well as pointers
and object IDs.
‣ NSValue uses type encoding to create the necessary
data structures to represent values internally
‣ valueWithNonretainedObject: allows objects to be
added to a collection, without the need for satisfying
<NSCopying> protocol

279. Thanks!
Massimo Oliviero
@maxoly