Objective.C中self.view.widow和[[UIApplication sharedApplication] keyWindow]之间的区别是什么

Question

如果我喜欢这个

var primeStringGenerator = ["60","52","81","61","85"].generate()
@IBOutlet var PrimeLabel: UILabel!

@IBAction func NewAction(sender: AnyObject) {
    PrimeLabel.text = primeGenerator.next() ?? "n/a"
}

然后在- (void)viewDidLoad { [super viewDidLoad]; UIAlertView *alert = [[UIAlertView alloc] initWithTitle:nil message:@"test" delegate:self cancelButtonTitle:@"ok" otherButtonTitles:nil]; [alert show]; } // Called when a button is clicked. The red view and alert will be automatically dismissed after this call returns - (void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex { [self showView]; } // after animation ,this will work fine - (void)alertView:(UIAlertView *)alertView didDismissWithButtonIndex:(NSInteger)buttonIndex { // [self showView]; } - (void)showView { // Called when a button is clicked. The view will be automatically dismissed after this call returns UIView *view = [[UIView alloc] init]; view.frame = CGRectMake(0, 0, 200, 200); view.backgroundColor = [UIColor redColor]; view.center = CGPointMake([UIScreen mainScreen].bounds.size.width/2.0f, [UIScreen mainScreen].bounds.size.height/2.0f); // [self.view.window addSubview:view]; //when i use this ,both of the two delegate methods works fine UIWindow *window = [[UIApplication sharedApplication] keyWindow]; [window addSubview:view]; } 调用返回

后，红色视图和警报将自动关闭

谁可以告诉我原因？

Objective.C中self.view.widow和[[UIApplication sharedApplication] keyWindow]之间的区别是什么

Answer 1

您的问题基本上在这里解决：

diffrence between [[[[UIApplication sharedApplication] delegate] window] and [[UIApplication sharedApplication].keyWindow?

要将它与问题联系起来，UIAlertView将显示在系统窗口中，而这个窗口是显示警报时的keyWindow。当警报被取消时，该窗口消失，因此您的视图消失的原因。

假设self.view是应用程序窗口的子视图（几乎总是如此），您的视图将继续显示，因为在关闭警报后窗口本身会继续显示。