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:];
         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     //
     }
     return ;
 }

　　  测试结果是:

-- ::36.408 -MRC[:] retaincount =
-- ::36.409 -MRC[:] retaincount =
-- ::36.410 -MRC[:] retaincount =
-- ::36.410 -MRC[:] retaincount =
-- ::36.410 -MRC[:] retaincount =
-- ::36.410 -MRC[:] retaincount =
-- ::36.410 -MRC[:] integer dealloc
Program ended with exit code: