iOS 视图层次管理 sendSubviewToBack、bringSubviewToFront

直接上代码

 - (void)viewDidLoad {
     [super viewDidLoad];
     // Do any additional setup after loading the view, typically from a nib.

     UIView *view1 = [[UIView alloc] initWithFrame:CGRectMake(10, 50, 100, 50)];
     view1.backgroundColor = [UIColor blueColor];
     [self.view addSubview:view1];

     UIView *view2 = [[UIView alloc] initWithFrame:CGRectMake(15, 55, 100, 50)];
     view2.backgroundColor = [UIColor grayColor];
     [self.view addSubview:view2];

     //如果将下面两行代码都注释掉   view1 会在下面   view2会在上面
     //  下面这行代码能够将view2  调整到父视图的最下面
 //    [self.view sendSubviewToBack:view2];
     //将view调整到父视图的最上面
     [self.view bringSubviewToFront:view1];

 }