set方法内存分析

//

//  main.m

//  04-set方法的内存管理分析

//

//  Created by apple on 14-3-17.

//

//

#import <Foundation/Foundation.h>

#import "Person.h"

int main(int argc, const char * argv[])

{

@autoreleasepool {

//p  1

Person * p = [[Person alloc] init];

// c1 1

Car * c1 = [[Car alloc] init];

c1.speed = 100;

//c1 2

[p setCar:c1];

[p drive];

//c1 1

[c1 release];

/*

[p setCar:c1];

[p drive];

*/

//c2 1

Car * c2 = [[Car alloc] init];

c2.speed = 350;

//c2  2

[p setCar:c2];

[p drive];

//c2 1

[c2 release];

//p 0

[p release];

}

return 0;

}

//

//  Person.m

//  01-手动内存管理基本概念

//

//  Created by apple on 14-3-17.

//

//

#import "Person.h"

//配对原则:new alloc retain 对应一个release,autorelease

@implementation Person

- (void)setName:(NSString *)name

{

if (_name != name)

{

[_name release];

_name = [name retain];

}

}

- (NSString *)name

{

return _name;

}

//解决三个问题：1，set多个不同car的时候，内存泄漏［ [_car release];//[nil release];］

2，set相同car的时候，野指针    ［ if (_car != car)］

3，调用方法是提前被销毁   ［_car  = [car retain];］

- (void)setCar:(Car *)car

{

if (_car != car)

{   //c1 0

//relese旧值

[_car release];//[nil release];

//c2 2

//retain新值

_car  = [car retain];

}

}

- (Car *)car

{

return _car;

}

- (void)drive

{

[_car run];

}

- (void)dealloc

{

//目的是要保证在p对象存在的时候,car对象一定存在

//对象p被销毁的时候,

//0

//c2 0

[_car release];

[_name release];

[super dealloc];

NSLog(@"Person 被销毁了");

}

@end