第二十讲：Objective-C内存管理之AutoreleasePool
黄金法则简述版： 如果对一个对象使用了 alloc、copy、retain，那么必须使用相应的release或者autorelease。前面已经有讲到过使用alloc、retain方法对retainCount进行内存管理，相对应地使用release进行内存释放，除此之外OC中引用较为智能的autorelease来进行内存管理，以下用一个程序进行说明：
Dog.h
//
//Dog.h
//AutoreleasePool
//
//Created by yusian on 14-1-12.
//Copyright (c) 2014年 yusian. All rights reserved.
//
#import <Foundation/Foundation.h>
@interface Dog : NSObject
{
int _ID;
}
@property int ID;
@endDog.m
//
//Dog.m
//AutoreleasePool
//
//Created by yusian on 14-1-12.
//Copyright (c) 2014年 yusian. All rights reserved.
//
#import "Dog.h"
@implementation Dog
@synthesize ID = _ID;
- (void) dealloc{
NSLog(@"dog is dealloc");
;
}
@end
main.m
//
//main.m
//AutoreleasePool
//
//Created by yusian on 14-1-12.
//Copyright (c) 2014年 yusian. All rights reserved.
//
#import <Foundation/Foundation.h>
#import "Dog.h"
int main(int argc, const char * argv[])
{
@autoreleasepool {
Dog * dog = [[ init] autorelease];
NSLog(@"dog retainCount1 is %ld",);
;
NSLog(@"dog retainCount2 is %ld",);
;
NSLog(@"dog retainCount3 is %ld",);
}
return 0;
}
输出结果：
2014-01-12 20:22:23.866 AutoreleasePool dog retainCount1 is 1
2014-01-12 20:22:23.868 AutoreleasePool dog retainCount2 is 2
2014-01-12 20:22:23.869 AutoreleasePool dog retainCount3 is 1
2014-01-12 20:22:23.869 AutoreleasePool dog is dealloc
Program ended with exit code: 0
@autoreleasepool{ }括号中的对象会被自动释放，无论对象被retain多少次，无论最终对象中retainCount值为多少，括号外面都无法再次使用该对象。上述例子中，最终为1，并没有人为释放，最终dog中的dealloc方法还是被调用，说明该对象已经被释放，即autoreleasepool实现。
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