Vietnam mobile day 2012 i os memory management - techmaster
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![[object release]
NSArray *array = [[NSArray alloc] initWithObjects:
@"Honda", @"Yamaha, nil];
NSLog(@Retain count: %d", [array retainCount]);
[array release];
RetainCount = 1
Honda
array Yamaha
Stack Heap
http://techmaster.vn](https://image.slidesharecdn.com/vietnammobileday2012-iosmemorymanagement-techmaster-120522052236-phpapp01/85/Vietnam-mobile-day-2012-i-os-memory-management-techmaster-8-320.jpg)
![NSArray *array = [[NSArray alloc] initWithObjects:
@"Honda", @"Yamaha, nil];
[array release];//C畉n ph畉i release
UIImage *aImage = [UIImage imageNamed:@A.png"];
[aImage release]; //Kh担ng c畉n ph畉i release. T畉I SAO?
http://techmaster.vn](https://image.slidesharecdn.com/vietnammobileday2012-iosmemorymanagement-techmaster-120522052236-phpapp01/85/Vietnam-mobile-day-2012-i-os-memory-management-techmaster-13-320.jpg)
![[UIImage imageNamed ] tr畉 v畛 畛i t動畛ng
autorelease (t畛 nh畉). Do 坦 kh担ng c畉n g畛i
message release 畉n 畛i t動畛ng ny n畛a.
http://techmaster.vn](https://image.slidesharecdn.com/vietnammobileday2012-iosmemorymanagement-techmaster-120522052236-phpapp01/85/Vietnam-mobile-day-2012-i-os-memory-management-techmaster-14-320.jpg)
![[object autorelease]
D湛ng khi t畉o m畛t object trong hm r畛i tr畉
v畛 qua return.
[object autorelease] : object s畉 動畛c qu畉n
l箪 trong AutoRelease pool
L畉m d畛ng autorelease kh担ng t畛t. T畉i sao?
http://techmaster.vn](https://image.slidesharecdn.com/vietnammobileday2012-iosmemorymanagement-techmaster-120522052236-phpapp01/85/Vietnam-mobile-day-2012-i-os-memory-management-techmaster-15-320.jpg)
![[object retain] d湛ng khi no?
NSArray *resultArray = [self returnAnArray];
NSArray *anotherArrayPointer = resultArray;
[resultArray release];
[anotherArrayPointer doSomething];
Bad memory access !d
http://techmaster.vn](https://image.slidesharecdn.com/vietnammobileday2012-iosmemorymanagement-techmaster-120522052236-phpapp01/85/Vietnam-mobile-day-2012-i-os-memory-management-techmaster-18-320.jpg)
![Tr動畛c khi chuy畛n con tr畛 畉n 畛i
t動畛ng kh叩c c畉n release 畛i t動畛ng c滴
objX
[p release]
*p
objY
Heap http://techmaster.vn](https://image.slidesharecdn.com/vietnammobileday2012-iosmemorymanagement-techmaster-120522052236-phpapp01/85/Vietnam-mobile-day-2012-i-os-memory-management-techmaster-19-320.jpg)
![G叩n strong pointer = nil 畛 hm viewDidUnload 畛
iOS gi畉i ph坦ng 畛i t動畛ng kh担ng c畉n d湛ng n畛a.
- (void)viewDidUnload
{
[super viewDidUnload];
myString = nil;
myImage = nil;
}
Kh担ng nh畉t thi畉t ph畉i d湛ng strong 畛 tr畛 t畛i
ph畉n t畛 giao di畛n trong XIB.
@property (nonatomic, weak) IBOutlet UIButton *myButton;
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Editor's Notes
- #2: http://stackoverflow.com/questions/6991142/writable-atomic-property-result-cannot-pair-a-synthesized-setter-getter-with-a
- #5: Objective-C is a thin layer on top of C, and moreover is a strict superset of C; it is possible to compile any C program with an Objective-C compiler, and to freely include C code within an Objective-C class.Objective-C derives its object syntax from Smalltalk. All of the syntax for non-object-oriented operations (including primitive variables, pre-processing, expressions, function declarations, and function calls) are identical to that of C, while the syntax for object-oriented features is an implementation of Smalltalk-style messaging.
- #16: http://www.asgteach.com/blog/?p=73
- #17: http://www.asgteach.com/blog/?p=73
- #33: http://stackoverflow.com/questions/7747783/is-arc-really-supported-in-ios-4-the-ios-4-2-sdk-is-missing-arc-related-symbols