Objective-C：MRC(引用计数器)获得对象所有权的方式(init、retain、copy等)

     .h声明文件

//  Integer.h
//  02-MRC
//
//  Created by ma c on 15/8/13.
//  Copyright (c) 2015年. All rights reserved.
//

#import <Foundation/Foundation.h>

@interface Integer : NSObject
@property(nonatomic,assign)NSInteger i;
-(id)initWithI:(NSInteger) i;
-(void) print;
+(Integer *)integerWithIntger:(NSInteger) i;
@end

　　.m实现文件

//  Integer.m
//  02-MRC
//
//  Created by ma c on 15/8/13.
//  Copyright (c) 2015年. All rights reserved.
//

#import "Integer.h"

@implementation Integer
-(id)initWithI:(NSInteger) i
{
    self = [super init];
    if(self)
    {
        _i = i;
    }
    return self;
}
+(Integer *)integerWithIntger:(NSInteger) i
{
    return [[Integer alloc]initWithI:i];
}

-(void) print
{
    NSLog(@"i = %ld",_i);
}
-(void)dealloc
{
    NSLog(@"integer dealloc");
    [super dealloc];
}
@end

　

　　　主函数测试

//  main.m
//  02-MRC
//
//  Created by ma c on 15/8/13.
//  Copyright (c) 2015年. All rights reserved.
//

#import <Foundation/Foundation.h>
#import "Integer.h"
int main(int argc, const char * argv[])
{
    @autoreleasepool
    {
        //测试手动引用计数
        //1.创建对象会获得对象所有权
        Integer *i1 = [[Integer alloc]initWithI:10];
        NSLog(@"retaincount = %lu",[i1 retainCount]);//1
        
        
        //2.只通过指针赋值，不会获得对象所有权
        Integer *i2 = i1;
        NSLog(@"retaincount = %lu",[i2 retainCount]);//1
        
        
        //3.通过retain会获得对象的所有权
        [i1 retain];
        NSLog(@"retaincount = %lu",[i1 retainCount]);//2
        
        
        //4.将对象添加到容器中,容器中会存储对象的一个引用,会获得对象所有权
        NSMutableArray *array = [NSMutableArray array];
        [array addObject:i1];
        NSLog(@"retaincount = %lu",[i1 retainCount]);//3
        
        
        //5.通过release释放对象的所有权
        [i1 release];
        NSLog(@"retaincount = %lu",[i1 retainCount]);//2
        
        
        //6.从容器中删除对象，也会释放对象所有权
        [array removeObject:i1];
        NSLog(@"retaincount = %lu",[i1 retainCount]);//1
        
        //7.最后再释放一次,对象才会被正常销毁
        [i1 release];  //此时,底层会调用dealloc方法     //0
    }
    return 0;
}

　　  测试结果是:

2015-08-13 17:32:36.408 02-MRC[1599:103515] retaincount = 1
2015-08-13 17:32:36.409 02-MRC[1599:103515] retaincount = 1
2015-08-13 17:32:36.410 02-MRC[1599:103515] retaincount = 2
2015-08-13 17:32:36.410 02-MRC[1599:103515] retaincount = 3
2015-08-13 17:32:36.410 02-MRC[1599:103515] retaincount = 2
2015-08-13 17:32:36.410 02-MRC[1599:103515] retaincount = 1
2015-08-13 17:32:36.410 02-MRC[1599:103515] integer dealloc
Program ended with exit code: 0