The document discusses memory management in Objective-C. It covers topics like when to create objects, instance variable scope, property attributes, setter methods, releasing objects, and sending messages to nil objects. Key terms mentioned include retain, release, copy, assign, autorelease, and properties like readonly, readwrite, strong, weak.

1. РАЗХВЪРЛЯНАТА
ПРЕЗЕНТАЦИЯ
Около първи етаж след основите
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2. DOT SYNTAX
set
(.) alternative to ([]) to invoke accessor methods
get
self.age = 10;
// Each member of the path is an object.
[self setAge:10];
x = person.address.street.name;
x = [[[person address] street] name];
// The path contains a C struct.
// This will crash if window is nil or -contentView
returns nil.
y = window.contentView.bounds.origin.y;
y = [[window contentView] bounds].origin.y;
// An example of using a setter.
person.address.street.name = @"Oxford Road";
[[[person address] street] setName: @"Oxford Road"];
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3. CHAPTER 2
Defining a Class
INSTANCE VARIABLES SCOPEFigure 2-‐1 illustrates the levels of scoping.
Figure 2-1 The scope of instance variables (@package scope not shown)
The class that
declares the @private
instance variable
@protected
A class that
inherits the @public
instance variable
Unrelated code
• default : @protected
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4. INSTANCE VARIABLES SCOPE
@interface Worker : NSObject
{
NSString *name;
@private
NSInteger age;
NSString *evaluation;
@protected
id job;
CGFloat wage;
@public
id boss;
}
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5. @property
@property float value;
@property(copy, readwrite) NSString *value;
@synthesize = напищи ми getter & setter
Access Memory
Multithreaded environment
(ARC)
readwrite - default strong (owning) By default, accessors are atomic.
readonly - only the getter method weak (non-owning)
nonatomic returns the value
directly
(MRC)
copy
The previous value is sent a release message.
NSCopying protocol.
assign
default. NSInteger, CGRect....
retain
upon assignment. The previous value is release-d
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6. MEMORY MANAGEMENT
Защо да създаваме обект:
• запазване на instance variable
• използване в метод
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7. MEMORY MANAGEMENT
Setter method
- (void)setLastUpdatedDate:(NSDate *)newDate {
! if (newDate) {
! ! [lastUpdatedDate release];
! ! lastUpdatedDate = [newDate retain];
}
}
//Recommended code:
-(void) setName: (NSString *) theName
{
[name release]
name = [[NSString alloc] initWthString: theName];
}
//Incorrect code according to Kochan:
-(void) setName: (NSString *) theName
{
[name release]
name = [NSString stringWthString: theName];
}
Thursday, December 22, 11

8. MEMORY MANAGEMENT
NSNumber* value1 = [[NSNumber alloc] initWithFloat:8.75];
[self setTotal:value1];
NSNumber* value2 = [NSNumber numberWithFloat:14.78];
[self setTotal:value2];
// only release value1
[value1 release];
Thursday, December 22, 11

9. MESSAGES TO NIL
[myArray release];
id anObjectMaybeNil = nil; myArray = nil;
// this is valid
if ([anObjectMaybeNil methodThatReturnsADouble] == 0.0)
{
// implementation continues...
}
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10. TTIMAGEVIEW
UIImageView
Name Link Title Note
TTImageView
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11. XCODE
• NSString
• .plist
• [NSUserDefaults standardUserDefaults]
• Custom UIImageView class
Thursday, December 22, 11