iOS 6.1.2-为什么不关闭UIAlertView？仍然在屏幕上的背景

这是我的代码:

UIAlertView *someError = [[UIAlertView alloc] initWithTitle:nil message:@"Server Error!" delegate:nil cancelButtonTitle: @"ok" otherButtonTitles: nil];
[someError show];

当我点击确定按钮时，警报背景仍然存在，并且我点击屏幕时，状态栏闪烁。

我找到了一些答案，但是它们不起作用，我将代码更改为:

dispatch_async(dispatch_get_main_queue(), ^{
       UIAlertView *someError = [[UIAlertView alloc] initWithTitle:nil message:@"Server Error!" delegate:nil cancelButtonTitle: @"ok" otherButtonTitles: nil];
       [someError show];
});

或设置代表:

dispatch_async(dispatch_get_main_queue(), ^{
       UIAlertView *someError = [[UIAlertView alloc] initWithTitle:nil message:@"Server Error!" delegate:self cancelButtonTitle: @"ok" otherButtonTitles: nil];
       [someError show];
});

-(void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
    dispatch_async(dispatch_get_main_queue(), ^{
        [alertView dismissWithClickedButtonIndex:buttonIndex animated:NO];
    });

}

它仍然不起作用，然后我尝试:

UIAlertView *someError = [[UIAlertView alloc] initWithTitle:nil message:@"error" delegate:nil cancelButtonTitle: @"ok" otherButtonTitles: nil];
[someError performSelectorOnMainThread:@selector(show) withObject:nil waitUntilDone:NO];

不能工作，疯狂，这也不能工作:

[self performSelectorOnMainThread:@selector(showAlert:) withObject:@"error", nil)  waitUntilDone:NO];

// the show Alert function
-(void)showAlert:(NSString*)str
{
    UIAlertView *someError = [[UIAlertView alloc] initWithTitle:nil message: str delegate: nil cancelButtonTitle: @"ok" otherButtonTitles: nil];
    [someError performSelectorOnMainThread:@selector(show) withObject:nil waitUntilDone:NO];
}

仍然无法正常工作。

警报显示前后:

最佳答案

确保您的 View Controller (或您从中创建UIAlertView的任何位置)在@interface行中定义了“<UIAlertViewDelegate>”。例如:

@interface YellowViewController : UIViewController <UIAlertViewDelegate>

现在，当您从子类化的 View Controller 创建UIAlertView并将委托(delegate)设置为self时，您的 View Controller 应符合并应接收委托(delegate)协议(protocol)方法。
下件事这段代码对我来说是正确的:

dispatch_async(dispatch_get_main_queue(), ^{
       UIAlertView *someError = [[UIAlertView alloc] initWithTitle:nil message:@"Server Error!" delegate:self cancelButtonTitle: @"ok" otherButtonTitles: nil];
       [someError show];
});

但是您的委托(delegate)方法调用将在主线程上发生(这是所有UI发生的地方):

-(void)alertView:(UIAlertView *)alertView clickedButtonAtIndex:(NSInteger)buttonIndex
{
    [alertView dismissWithClickedButtonIndex:buttonIndex YES];
}

换句话说，摆脱那里的调度程序，看看会发生什么。再一次，the Apple documentation for " clickedButtonAtIndex: " says:

因此，您可能不需要实际显式关闭警报 View 。

关于iOS 6.1.2-为什么不关闭UIAlertView？仍然在屏幕上的背景，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/16248558/