我可以在显示UIAlertView时收到消息

Question

我想在系统显示UIAlertView时收到消息,这样我就可以暂停游戏了.

谁知道怎么弄明白？

UIAlertView不受我自己的控制.

Answer 1

系统警报通常以其自身显示UIWindow.安装处理程序UIWindowDidBecomeVisibleNotification和UIWindowDidBecomeHiddenNotification通知以跟踪何时UIWindow分别变为可见和隐藏:

 [[NSNotificationCenter defaultCenter] addObserver:self
                                          selector:@selector(aWindowBecameVisible:)
                                              name:UIWindowDidBecomeVisibleNotification
                                            object:nil];
 [[NSNotificationCenter defaultCenter] addObserver:self
                                          selector:@selector(aWindowBecameHidden:)
                                              name:UIWindowDidBecomeHiddenNotification
                                            object:nil];

在处理程序中,UIWindow从object通知的属性中获取该更改状态:

- (void)aWindowBecameVisible:(NSNotification *)notification
{
    UIWindow *theWindow = [notification object];
    NSLog(@"Window just shown: %@", theWindow);
}

- (void)aWindowBecameHidden:(NSNotification *)notification
{
    UIWindow *theWindow = [notification object];
    NSLog(@"Window just hidden: %@", theWindow);
}

最后,检查theWindow包含类型的子视图UIAlertView.