MRC内存管理（二）数组、控件

我就是我 2023-10-17 03:56 20阅读 0赞

续上一篇[MRC内存管理（一）][MRC]

- (void)viewDidLoad {
        [super viewDidLoad];
        NSObject *obj = [[NSObject alloc] init];
        
        NSLog(@"对象－－%lu",(unsigned long)obj.retainCount);
        
            //当把对象放入数组中时，数组会对这个对象引用计数+1.
        NSMutableArray *array = [[NSMutableArray alloc] initWithObjects:obj, nil];
        NSLog(@"加入数组对象－－%lu",(unsigned long)obj.retainCount);
        
            //把对象从数组中移除时，对象的引用计数-1.
        [array removeObject:obj];
        NSLog(@"移除数组对象－－%lu",(unsigned long)obj.retainCount);
            //当数组本身被释放前，会对自己内部所有的对象release一次。
        
        UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(20, 40, 200, 40)];
        label.text = @"123";
        NSLog(@"控件对象－－%lu",(unsigned long)label.retainCount);
        
            //当把视图添加到父视图时，父视图会对这个视图retain一次。
        [self.view addSubview:label];
        NSLog(@"加入父视图－－%lu",(unsigned long)label.retainCount);
        
            //当视图从父视图移除时，引用计数-1
            //[label removeFromSuperview];
        
            //当视图释放前，会对自身所有的子视图release一次
        [label release];
    }
    
    - (IBAction)showAlertClick:(UIButton *)sender {
        UIAlertView *alert = [[UIAlertView alloc] initWithTitle:@"标题" message:@"消息" delegate:nil cancelButtonTitle:@"取消" otherButtonTitles:@"确定", nil];
        NSLog(@"alert－－%lu",(unsigned long)alert.retainCount);
            //show会导致alert的引用计数增加。
        [alert show];
        NSLog(@"show－－%lu",(unsigned long)alert.retainCount);
        [alert release];
    }
    
    - (IBAction)presentViewController:(UIButton *)sender {
        SecondVC *vc = [[SecondVC alloc] init];
        NSLog(@"创建VC－－%lu",(unsigned long)vc.retainCount);
            //presentViewController模态弹出
            //模态弹出会导致vc引用计数增加
        [self presentViewController:vc animated:YES completion:nil];
        NSLog(@"模态弹出－－%lu",(unsigned long)vc.retainCount);
        [vc release];
    }

输出结果如下：

![Center][]

至于一个模态弹出为何输出引用计数这么大，博主也甚是不解，望广大友人给予帮忙解释一下，感激不尽，谢谢！

[MRC]: http://blog.csdn.net/minggeqingchun/article/details/51759398
[Center]: https://img-blog.csdn.net/20160625175903015?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQv/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center