释放池，指针

//
//  main.m
//  test
//
//  Created by myhaspl on 16/11/4.
//  Copyright (c) 2016年 myhaspl@myhaspl.com. All rights reserved.
//

#import <Foundation/Foundation.h>

int main(int argc, const char * argv[]) {
    //@autoreleasepool {
        // insert code here...
    
        //手动释放
        NSNumber *mynum=[[NSNumber alloc]initWithDouble:3.1415926];
        NSLog(@"引用计数为：%lu",(unsigned long)[mynum retainCount]);
        NSNumber * mynum1=mynum;
        [mynum retain];
        NSLog(@"引用计数为：%lu",(unsigned long)[mynum retainCount]);
        NSNumber * mynum2=mynum;
        [mynum retain];
        NSLog(@"引用计数为：%lu",(unsigned long)[mynum retainCount]);
        [mynum retain];
        NSLog(@"引用计数为：%lu",(unsigned long)[mynum retainCount]);
        [mynum release];
        NSLog(@"引用计数为：%lu",(unsigned long)[mynum retainCount]);
        [mynum release];
        NSLog(@"引用计数为：%lu",(unsigned long)[mynum retainCount]);
        [mynum release];
        NSLog(@"引用计数为：%lu",(unsigned long)[mynum retainCount]);
    
        //自动释放池1
        //@autoreleasepool {
          // Objective-C的Auto Reference Counting为YES
        // }
       NSLog(@"自动释放池2");
       //自动释放池2  Objective-C的Auto Reference Counting为NO
       //@autoreleasepool {
       NSAutoreleasePool *pool=[[NSAutoreleasePool alloc]init];//创建池
       NSNumber *yournum=[[NSNumber alloc]initWithDouble:3.1415926];
       NSLog(@"引用计数为：%lu",(unsigned long)[yournum retainCount]);
       [yournum  autorelease];
       [yournum  autorelease];
       [yournum retain];
       [yournum retain];
       NSLog(@"引用计数为：%lu",(unsigned long)[yournum retainCount]);
       [pool drain];
       NSLog(@"引用计数为：%lu",(unsigned long)[yournum retainCount]);
    
    
    
    
    return 0;
}

2016-11-04 16:40:41.411 test[710:22710] 引用计数为：1

2016-11-04 16:40:41.412 test[710:22710] 引用计数为：2

2016-11-04 16:40:41.412 test[710:22710] 引用计数为：3

2016-11-04 16:40:41.413 test[710:22710] 引用计数为：4

2016-11-04 16:40:41.413 test[710:22710] 引用计数为：3

2016-11-04 16:40:41.413 test[710:22710] 引用计数为：2

2016-11-04 16:40:41.413 test[710:22710] 引用计数为：1

2016-11-04 16:40:41.413 test[710:22710] 自动释放池2

2016-11-04 16:40:41.413 test[710:22710] 引用计数为：1

2016-11-04 16:40:41.414 test[710:22710] 引用计数为：3

2016-11-04 16:40:41.414 test[710:22710] 引用计数为：1