ios - KeyWindow 添加子View，没有显示在最前面

Question

我用keyWindow添加了一个subView，添加成功但是没有显示在screen hierarchy的最前面。

深灰色 View 是我添加的 View :

我的代码是:

@interface ViewController ()
{
    LMLUpspringView *pop_v;
}

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];

    pop_v = [[LMLUpspringView alloc] initWithFrame:CGRectMake(0, 0, self.view.bounds.size.width, self.view.bounds.size.height)];

    UIWindow *keywindow = [[[UIApplication sharedApplication] delegate] window];

    [keywindow addSubview:pop_v];

    //[keywindow bringSubviewToFront:pop_v];
    //[self.view addSubview:pop_v];

}

我试过使用 [keywindow bringSubviewToFront:pop_v] 把它带到前面。但是没有用。

如果我使用[self.view addSubview:pop_v]，它会显示在前面。

Answer 1

您遇到这个问题，是因为您不知道viewDidLoad 方法和viewDidAppear: 方法之间的区别。

viewWillAppear:

Called before the view is added to the windows’ view hierarchy

viewDidAppear:

Called after the view is added to the view hierarchy

添加到窗口 View 层级的 Controller View 在viewWillAppear:和viewDidAppear:之间，viewDidLoad在之前viewWillAppear:，所以你不能那样做。您应该在 viewDidAppear: 中添加您的 View 。