iOS 6.1.2 - 为什么UIAlertView不被解雇？背景仍然在屏幕上

Question

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,我点击屏幕,状态栏闪烁.

我找到了一些答案,但它们不起作用,我将我的代码更改为:

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];

不工作,疯了,这也不行:

[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];
}

还是不行.

警报显示前后:

Answer 1

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

@interface YellowViewController : UIViewController <UIAlertViewDelegate>

现在，当您从子类视图控制器创建 UIAlertView 并将委托设置为 self 时，您的视图控制器应该符合并应该接收委托协议方法。

接下来的事情。这段代码对我来说看起来是正确的：

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，去掉里面的调度东西，看看会发生什么。话又说回来，“”的苹果文档clickedButtonAtIndex:说：

讨论

调用此方法后，接收器将自动关闭。

因此，您可能不需要实际显式地关闭警报视图。