第十七讲：Objective-C黄金法则之"点语法"

Sian · 发表于 2014-1-12 11:55:45

本帖最后由 Sian 于 2014-1-12 11:58 编辑

本讲是针对第十六讲黄金法则中retain与release关系的优化，却retain属性：@property (retain)
Dog.h

//
// Dog.h
// Memory_retain
//
// 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;
@end

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Dog.m

//
// Dog.m
// Memory_retain
//
// 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 %d is dealloc",_ID);
[super dealloc];
}
@end

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Person.h

//
// Person.h
// Memory_retain
//
// Created by yusian on 14-1-12.
// Copyright (c) 2014年 yusian. All rights reserved.
//
#import <Foundation/Foundation.h>
#import "Dog.h"
@interface Person : NSObject
@property (retain) Dog * dog;
@end

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Person.m

//
// Person.m
// Memory_retain
//
// Created by yusian on 14-1-12.
// Copyright (c) 2014年 yusian. All rights reserved.
//
#import "Person.h"
@implementation Person
@synthesize dog = _dog;
- (void) dealloc{
self.dog = nil;
NSLog(@"Person is dealloc");
[super dealloc];
}
@end

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main.m

//
// main.m
// Memory_retain
//
// Created by yusian on 14-1-12.
//
#import <Foundation/Foundation.h>
#import "Dog.h"
#import "Person.h"
int main(int argc, const char * argv[])
{
@autoreleasepool {
Dog * dog1 = [[Dog alloc] init];
Dog * dog2 = [[Dog alloc] init];
Person * sim = [[Person alloc] init];
Person * sian = [[Person alloc] init];
[dog1 setID:1];
[dog2 setID:2];
NSLog(@"//初始化后的retainCount值");
NSLog(@"dog %d retainCount1 is %ld",[dog1 ID],[dog1 retainCount]);
NSLog(@"dog %d retainCount1 is %ld",[dog2 ID],[dog2 retainCount]);
[sim setDog:dog1];
NSLog(@"//sim开始遛狗dog1");
NSLog(@"dog %d retainCount2 is %ld",[dog1 ID],[dog1 retainCount]);
NSLog(@"dog %d retainCount2 is %ld",[dog2 ID],[dog2 retainCount]);
[sian setDog:dog2];
NSLog(@"//sian开始遛狗dog2");
NSLog(@"dog %d retainCount3 is %ld",[dog1 ID],[dog1 retainCount]);
NSLog(@"dog %d retainCount3 is %ld",[dog2 ID],[dog2 retainCount]);
[sim setDog:dog2];
[sian setDog:dog1];
NSLog(@"//sim和sian交换遛狗");
NSLog(@"dog %d retainCount4 is %ld",[dog1 ID],[dog1 retainCount]);
NSLog(@"dog %d retainCount4 is %ld",[dog2 ID],[dog2 retainCount]);
[sim setDog:dog1];
NSLog(@"//sim和sian都转为遛狗dog1");
NSLog(@"dog %d retainCount5 is %ld",[dog1 ID],[dog1 retainCount]);
NSLog(@"dog %d retainCount5 is %ld",[dog2 ID],[dog2 retainCount]);
[sim setDog:dog2];
[sian setDog:dog2];
NSLog(@"//sim和sian都转为遛狗dog2");
NSLog(@"dog %d retainCount6 is %ld",[dog1 ID],[dog1 retainCount]);
NSLog(@"dog %d retainCount6 is %ld",[dog2 ID],[dog2 retainCount]);
NSLog(@"//sim离开");
[sim release];
NSLog(@"dog %d retainCount7 is %ld",[dog1 ID],[dog1 retainCount]);
NSLog(@"dog %d retainCount7 is %ld",[dog2 ID],[dog2 retainCount]);
NSLog(@"//sian离开");
[sian release];
NSLog(@"dog %d retainCount8 is %ld",[dog1 ID],[dog1 retainCount]);
NSLog(@"dog %d retainCount8 is %ld",[dog2 ID],[dog2 retainCount]);
NSLog(@"//dog1 and dog2 release");
[dog1 release];
[dog2 release];
}
return 0;
}

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输出结果为：

2014-01-12 11:50:01.862 Memory_retain[1767:303] //初始化后的retainCount值
2014-01-12 11:50:01.864 Memory_retain[1767:303] dog 1 retainCount1 is 1
2014-01-12 11:50:01.864 Memory_retain[1767:303] dog 2 retainCount1 is 1
2014-01-12 11:50:01.865 Memory_retain[1767:303] //sim开始遛狗dog1
2014-01-12 11:50:01.865 Memory_retain[1767:303] dog 1 retainCount2 is 2
2014-01-12 11:50:01.865 Memory_retain[1767:303] dog 2 retainCount2 is 1
2014-01-12 11:50:01.866 Memory_retain[1767:303] //sian开始遛狗dog2
2014-01-12 11:50:01.866 Memory_retain[1767:303] dog 1 retainCount3 is 2
2014-01-12 11:50:01.867 Memory_retain[1767:303] dog 2 retainCount3 is 2
2014-01-12 11:50:01.867 Memory_retain[1767:303] //sim和sian交换遛狗
2014-01-12 11:50:01.867 Memory_retain[1767:303] dog 1 retainCount4 is 2
2014-01-12 11:50:01.868 Memory_retain[1767:303] dog 2 retainCount4 is 2
2014-01-12 11:50:01.868 Memory_retain[1767:303] //sim和sian都转为遛狗dog1
2014-01-12 11:50:01.868 Memory_retain[1767:303] dog 1 retainCount5 is 3
2014-01-12 11:50:01.868 Memory_retain[1767:303] dog 2 retainCount5 is 1
2014-01-12 11:50:01.869 Memory_retain[1767:303] //sim和sian都转为遛狗dog2
2014-01-12 11:50:01.869 Memory_retain[1767:303] dog 1 retainCount6 is 1
2014-01-12 11:50:01.879 Memory_retain[1767:303] dog 2 retainCount6 is 3
2014-01-12 11:50:01.879 Memory_retain[1767:303] //sim离开
2014-01-12 11:50:01.880 Memory_retain[1767:303] Person is dealloc
2014-01-12 11:50:01.880 Memory_retain[1767:303] dog 1 retainCount7 is 1
2014-01-12 11:50:01.880 Memory_retain[1767:303] dog 2 retainCount7 is 2
2014-01-12 11:50:01.881 Memory_retain[1767:303] //sian离开
2014-01-12 11:50:01.881 Memory_retain[1767:303] Person is dealloc
2014-01-12 11:50:01.881 Memory_retain[1767:303] dog 1 retainCount8 is 1
2014-01-12 11:50:01.882 Memory_retain[1767:303] dog 2 retainCount8 is 1
2014-01-12 11:50:01.882 Memory_retain[1767:303] //dog1 and dog2 release
2014-01-12 11:50:01.883 Memory_retain[1767:303] dog 1 is dealloc
2014-01-12 11:50:01.883 Memory_retain[1767:303] dog 2 is dealloc
Program ended with exit code: 0

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