OC MRC之循环引用问题（代码分析）

//
//  main.m
//  07-循环引用
//
//  Created by apple on 13-8-9.
//  Copyright (c) 2013年 itcast. All rights reserved.
//

/*
1.@class的作用：仅仅告诉编译器，某个名称是一个类
@class Person; // 仅仅告诉编译器，Person是一个类

2.开发中引用一个类的规范
1> 在.h文件中用@class来声明类
2> 在.m文件中用#import来包含类的所有东西

3.两端循环引用解决方案
1> 一端用retain
2> 一端用assign

*/

#import <Foundation/Foundation.h>
#import "Card.h"
// @class仅仅是告诉编译器，Card是一个类
//@class Card;

@interface Person : NSObject

@property (nonatomic, retain) Card *card;

@end

#import "Person.h"
#import "Card.h"

@implementation Person

- (void)dealloc
{
NSLog(@"Person被销毁了");
[_card release];

[super dealloc];
}

@end

#import <Foundation/Foundation.h>

@class Person;

@interface Card : NSObject

@property (nonatomic, assign) Person *person;

@end

#import "Card.h"
#import "Person.h"

@implementation Card

- (void)dealloc
{
NSLog(@"Car被销毁了");

// [_person release];

[super dealloc];
}

@end

#import <Foundation/Foundation.h>
#import "Card.h"
#import "Person.h"

int main()
{
// p - 1
Person *p = [[Person alloc] init];
// c - 1
Card *c = [[Card alloc] init];

// c - 2
p.card = c;

// p - 1
c.person = p;

// c - 1
[c release];

// p - 0  c - 0
[p release];
return 0;
}