OC 内存管理

//
//  main.m
//  oc04_内存管理
//
//  Created by Vision on 14-9-16.
//  Copyright (c) 2014年 Vision. All rights reserved.
//

#import <Foundation/Foundation.h>
#import "House.h"
#import "Person.h"
int main(int argc, const char * argv[])
{

    @autoreleasepool {
        //野指针
        //错误1：指向访问受限的内存区域
        int *p = 0x0001;
        NSLog(@"%d", *p);
        //错误2：指向已经回收的内存区域
        int *q = malloc(sizeof(int));
        *q = 4;
        free(q);
        NSLog(@"%d",*q);
        *q = 5;
        NSLog(@"%d",*q);
        
    }
    @autoreleasepool {
    
        //1.alloc
        House *xiaoGuiZiHouse = [[House alloc]init];
      
        //2.retain
        NSLog(@"%lu", [xiaoGuiZiHouse retainCount]);
        House *jiaHongHouse = [xiaoGuiZiHouse retain];
        NSLog(@"%lu", [xiaoGuiZiHouse retainCount]);
        NSLog(@"%lu", [jiaHongHouse retainCount]);
        House *zijieHouse = [xiaoGuiZiHouse retain];
        NSLog(@"%lu", [zijieHouse retainCount]);
       
        //3.release
        [zijieHouse release];
        zijieHouse = nil;//防止野指针
        [jiaHongHouse release];
        jiaHongHouse = nil;
        [xiaoGuiZiHouse autorelease];
         NSLog(@"%lu", [xiaoGuiZiHouse retainCount]);
        // 1 -> 0过程观察不到
        //[nil retainCount] == 0
        
    }
  
    
    House *house = [[House alloc]init];
    @autoreleasepool {
        [house retain];
        NSLog(@"%lu",[house retainCount]);
        [house autorelease];//引用计数暂时不变
        NSLog(@"%lu",[house retainCount]);

        
    }
    //引用计数 - 1
    NSLog(@"%lu",[house retainCount]);
    @autoreleasepool {
        House *hunFang = [[[House alloc]init] autorelease];// 防止忘记release ，或不确定何时release
}

    @autoreleasepool {
        Person *erMu = [[Person alloc]initWithName:@"二木"];
        Person *yuYuan = [[Person alloc]initWithName:@"余元"];
        Person *dongHai = [[Person alloc]initWithName:@"东海"];
        [erMu autorelease];
        [yuYuan autorelease];
        [dongHai autorelease];
        Person *liHongXun = [erMu retain];
        [liHongXun release];
        
        Person *guiChua = [[Person alloc]initWithName:@"鬼船"];
        Person *guiChuanClone = [guiChua copy];
        [guiChuanClone release];
        
        
        Person *yaNan = [Person personWithName:@"亚楠"];
        //注意：便利构造器创建的对象无需额外release
    }
    return 0;
}
<pre name="code" class="objc">//
//  House.h
//  oc04_内存管理
//
//  Created by Vision on 14-9-16.
//  Copyright (c) 2014年 Vision. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface House : NSObject

@end

//
//  House.m
//  oc04_内存管理
//
//  Created by Vision on 14-9-16.
//  Copyright (c) 2014年 Vision. All rights reserved.
//

#import "House.h"

@implementation House

@end

//
//  Person.h
//  oc04_内存管理
//
//  Created by Vision on 14-9-16.
//  Copyright (c) 2014年 Vision. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface Person : NSObject<NSCopying>
{
    NSString *_name;
}
- (id)initWithName:(NSString *)name;
- (id)copyWithZone:(NSZone *)zone;
+ (id)personWithName:(NSString *)name;
@end

//
//  Person.m
//  oc04_内存管理
//
//  Created by Vision on 14-9-16.
//  Copyright (c) 2014年 Vision. All rights reserved.
//

#import "Person.h"

@implementation Person
- (id)initWithName:(NSString *)name
{
    self = [super init];
    if (self) {
        _name = name;
    }
    return self;
}
- (void)dealloc
{
    NSLog(@"%@被释放了个屁的",
          _name);
    [super dealloc];
}

- (id)copyWithZone:(NSZone *)zone
{
    Person *p = [[Person allocWithZone:zone]initWithName:[NSString stringWithFormat:@"%@的克隆人",
                                                          _name]];
    return p;
}
+ (id)personWithName:(NSString *)name
{
    return [[[Person alloc]initWithName:name]autorelease];
}
@end