The document discusses the speaker's experience transitioning from Ruby to Objective-C for iOS app development. Some key points of comparison between the two languages are their object-oriented nature, use of messages and blocks, and common ancestry in Smalltalk. The speaker notes advantages of Ruby's ecosystem with Rails but also that Cocoa is the more difficult part of iOS development versus Objective-C itself. Overall, the experience of developing iOS apps draws from backgrounds in Ruby, C/C++, and Flash.

2. from Ruby to Objective-C

4. I’m a Flash guy (≈ 9 years)
I’m a Python guy (≈ 3 years)
I’m a Ruby guy (≈ 5 years)
I’m a iOS app guy (≈ 3 years)

5. Ruby > Rails

6. Current Status
80% iOS app, 20% Ruby/Rails

7. 100% Ruby Lover!

8. Rails Girls Taipei

9. Rails Girls Taipei

10. WebConf Taiwan 2014

11. Today, I’m NOT talking about..
how to use Ruby to write iOS app!

12. I’m going to talk about..

13. what I learned in Ruby…

14. and move to Objective-C

15. after all, our life, time and
resources are limited

17. what about Objective-C?

18. Objective-C …
“it has god dame long method name
and weird parameters!”
NSArray* languages = [NSArray arrayWithObjects:@"Ruby", @"PHP",
@"Objective-C", nil];
!
[languages enumerateObjectsUsingBlock:^(id obj, NSUInteger idx, BOOL
*stop) {
NSLog(@"language = %@", obj);
}];

19. Objective-C …
“what the hell is the square bracket!”
NSString* myName = @"eddie kao";
NSLog(@"%@", [myName uppercaseString]);

20. Objective-C …
“WTF! my app crashed again!!”

21. Introduction

22. Ruby was born on 1993
Objective-C was born on 1983

23. they have the same ancestor

24. Smalltalk
photo by Marcin Wichary

25. Ruby is general-purpose
Objective-C mainly used in
Mac/iOS app development

26. Ruby != Rails
Objective-C != Cocoa Framework

27. they have something in common..

28. both Ruby and Objective-C are
Object-Oriented

29. both Ruby and Objective-C are
strongly typed language.

30. Ruby is a dynamic language
Objective-C is a dynamic language

31. both Ruby and Objective-C are
Dynamic Typing

32. Type checking..
- (void) makeSomeNoise:(id) sender
{
if ([sender isKindOfClass:[RobberDuck class]])
{
RobberDuck* duck = (RobberDuck *) sender;
[duck quack];
}
}

33. or you can do this..
- (void) makeSomeNoise:(id) sender
{
if ([sender respondsToSelector:@selector(quack)])
{
[sender quack];
}
}

35. id

36. Objective-C is superset of C

37. Objective-C is still C

38. NSString, NSArray, NSNumber…

39. NextSTEP

40. CF… = Core Foundation
CG… = Core Graphic
CL… = Core Location
CA… = Core Animation
UI… = User Interface

41. OOP

42. everything in Ruby is an object…

43. and almost everything in
Objective-C is an objects..

44. there’re still some primitive data
types in Objective-C

45. object model
class Animal
end
!
class Dog < Animal
end

46. object model
dog = Dog.new
!
puts "class of dog is #{dog.class}”
# Dog
puts "superclass of dog is #{dog.class.superclass}” # Animal
puts "super superclass of dog is
#{dog.class.superclass.superclass}”
# Object
puts "super super superclass of dog is
#{dog.class.superclass.superclass.superclass}” # BasicObject
!
puts
puts
puts
puts
"class
"class
"class
"class
of Dog is #{Dog.class}”
class of Dog is #{Dog.class.class}”
of Animal is #{Animal.class}”
of Object is #{Object.class}”
#
#
#
#
Class
Class
Class
Class

47. object model
@interface Animal : NSObject
@end
!
@implementation Animal
@end
!
@interface Dog : Animal
@end
!
@implementation Dog
@end

48. object model
Dog* dog = [[Dog alloc] init];
!
NSLog(@"class of dog is %@", [dog class]); # Dog
!
NSLog(@"superclass of dog is %@", [dog superclass]); # Animal
!
NSLog(@"super superclass of dog is %@", [[dog superclass] superclass]); #
NSObject
!
NSLog(@"super super superclass of dog is %@", [[[dog superclass]
superclass] superclass]); # null

49. Object Model
reference: http://goo.gl/wYL6gT

50. method & message

51. method definition
def say_hello(someone, message)
puts "Hello #{someone}, #{message}"
end
- (void) sayHello:(id)someOne withMessage:(NSString *)message
{
NSLog(@"Hello %@, %@", someOne, message);
}

52. sending message
dog.walk()
[dog walk];
# or you can omit the parentheses

53. sending message
fox.say_something "hi, Ruby"
[fox saySomething:@"hi, Ruby"];
# what does the fox say?

54. sending message
puts 1 + 2
puts 1.+(2)
puts 1.send(:+, 2)

55. sending message
class Bank
def save(money)
puts "you just saved #{money} dollars"
end
end
!
bank = Bank.new
bank.save 20
bank.send(:save, 20)
# you just saved 20 dollars
# you just saved 20 dollars

56. sending message
@interface Bank : NSObject
- (void) save:(NSNumber *) money;
@end
!
@implementation Bank
- (void)save:(NSNumber *)money
{
NSLog(@"you just saved %@ dollars", money);
}
@end
!
Bank* bank = [[Bank alloc] init];
[bank save:@20];
[bank performSelector:@selector(save:) withObject:@20];

57. block

58. block
p1 = Proc.new { puts "Hello, Proc Block" }
p1.call
!
p2 = lambda { puts "Hello, Lambda Block" }
p2.call

59. block
^{ };

60. block
typedef void (^MyBlock)(void);
int age = 18;
MyBlock theBlock = ^{
NSLog(@"Hello, Objective-C Block, your age = %d", age);
};
!
theBlock();
# Hello, Objective-C Block, your age = 18
!
age = 38;
theBlock();
# guess what’s the age?

61. block
3.times { |i| puts i }
NSArray* list = @[@1, @2, @3];
[list enumerateObjectsUsingBlock:^(NSNumber* num,
NSUInteger idx, BOOL *stop) {
NSLog(@"%@", num);
}];

62. iteration

63. iteration
list = [1, 2, 3, 4, 5]
!
sum = 0
!
list.each { |num|
sum += num
}
!
puts "sum = #{sum}"

64. iteration
NSArray* list = @[@1, @2, @3, @4, @5];
!
__block int sum = 0;
!
[list enumerateObjectsUsingBlock:^(NSNumber* num,
NSUInteger idx, BOOL *stop) {
sum += [num intValue];
}];
!
NSLog(@"sum = %d", sum);

65. iteration
class Fox
def say
puts "what does the fox say?"
end
end
!
fox1 = Fox.new
fox2 = Fox.new
fox3 = Fox.new
foxes = [fox1, fox2, fox3]
!
foxes.map { |fox| fox.say }
# what does the fox say?

66. iteration
@interface Fox : NSObject
- (void) say;
@end
!
@implementation Fox
- (void) say
{
NSLog(@"what does the fox say?!");
}
@end

67. iteration
Fox* fox1 = [[Fox alloc] init];
Fox* fox2 = [[Fox alloc] init];
Fox* fox3 = [[Fox alloc] init];
!
NSArray* foxes = @[fox1, fox2, fox3];
!
[foxes makeObjectsPerformSelector:@selector(say)];

68. add methods at runtime

69. Open class
class String
def is_awesome?
return true if self == "Ruby Tuesday"
end
end
!
puts "Ruby Tuesday".is_awesome?

70. Category
@interface NSString(RubyTuesday)
- (BOOL) isAwesome;
@end
!
@implementation NSString(RubyTuesday)
- (BOOL) isAwesome
{
if ([self isEqualToString:@"Ruby Tuesday"]){
return YES;
}
return NO;
}
@end

71. Category
NSString* meetup = @"Ruby Tuesday";
if ([meetup isAwesome])
{
NSLog(@"AWESOME!");
}

72. <objc/runtime.h>
Working with Classes
class_getName
class_getSuperclass
class_getInstanceVariable
class_getClassVariable
class_addIvar
class_copyIvarList
class_addMethod
class_getInstanceMethod
class_getClassMethod
class_replaceMethod
class_respondsToSelector
..
reference: http://goo.gl/BEikIM

73. <objc/runtime.h>
Working with Instances
object_copy
object_dispose
object_setInstanceVariable
object_getInstanceVariable
object_getIndexedIvars
object_getIvar
object_setIvar
object_getClassName
object_getClass
object_setClass
..
reference: http://goo.gl/BEikIM

74. reflection
-
(BOOL)
(BOOL)
(BOOL)
(BOOL)
..
isKindOfClass:(Class) aClass
isMemberOfClass:(Class) aClass
respondsToSelector:(SEL) aSelector
conformsToProtocol:(Protocol *) aProtocol
reference: http://goo.gl/fgmJcg

75. ecosystem

76. open source projects on Github
Ruby : 76,574
Objective-C : 22,959

77. Ruby : bundler
source 'https://rubygems.org'
!
gem 'rails', '3.2.8'
gem 'mysql2'
!
group :assets do
gem 'sass-rails',
'~> 3.2.3'
gem "bootstrap-sass"
end
!
gem
gem
gem
gem
"kaminari"
"simple_form"
"carrierwave"
'unicorn'

78. Objective-C : cocoapods
platform :ios, '6.0'
!
pod
pod
pod
pod
pod
pod
'Facebook-iOS-SDK', '~> 3.5.1’
'JSONKit', '~> 1.5pre'
'MagicalRecord', '~> 2.0.7’
'SSKeychain', '~> 0.1.4’
'TestFlightSDK', '~> 1.1'
'SMCalloutView', '~> 1.1.2'
!
target :UnitTests do
link_with 'UnitTests'
pod 'OCMock', '~> 2.0.1'
pod 'OCHamcrest', '~> 1.9'
end

79. IMHO

80. Objective-C is not really hard to
learn…

81. the actual difficult part in iOS app
development is Cocoa Framework

82. Objective-C would be almost
useless without Cocoa Framework

83. Ruby without Rails?!

84. design patterns
MVC
observer
notifications singleton
delegation
command
composite
target-action
proxy

85. C

86. what else..

87. photoed by JD Hancock

89. Flash Display Hierarchy
reference: http://goo.gl/2mzyMY

90. UIKit and AppKit framework Hierarchy
reference: http://goo.gl/xhS7m7

91. Views
reference: http://goo.gl/xhS7m7

92. Views
reference: http://goo.gl/xhS7m7

93. and I read Ruby source code..

94. my iOS app dev experience
= Ruby + C + Flash/AS3
=
+

95. Contacts
⾼高⾒見⻯⿓龍
Website
http://www.eddie.com.tw
Blog
http://blog.eddie.com.tw
Plurk
http://www.plurk.com/aquarianboy
Facebook
http://www.facebook.com/eddiekao
Google Plus
http://www.eddie.com.tw/+
Twitter
https://twitter.com/#!/eddiekao
Email
eddie@digik.com.tw
Mobile
+886-928-617-687
photo by Eddie