UIAlertController警告消息

Question

我在我的项目中使用了下面的UIAlertController代码。

if([[[UIDevice currentDevice] systemVersion]floatValue] >= 8.0){

            UIAlertController * alert=   [UIAlertController
                                          alertControllerWithTitle:@"Input Error"
                                          message:@"Please enter a valid email."
                                          preferredStyle:UIAlertControllerStyleAlert];

            UIAlertAction* okAction = [UIAlertAction
                                       actionWithTitle:@"OK"
                                       style:UIAlertActionStyleDefault
                                       handler:^(UIAlertAction * action)
                                       {
                                           [alert dismissViewControllerAnimated:YES completion:nil];

                                       }];

            [alert addAction:okAction];

            [self presentViewController:alert animated:YES completion:nil];
        }
        else
        {
        UIAlertView *alertView = [[UIAlertView alloc] initWithTitle:@"Input Error"
                                                            message:@"Please enter a valid email"
                                                           delegate:self
                                                  cancelButtonTitle:@"OK"
                                                  otherButtonTitles:nil, nil];
        [alertView show];
        }

我收到以下警告消息：

Warning: Attempt to present <UIAlertController: 0x7f8da58df1f0>  on <MBComplaintsViewController: 0x7f8da36454d0> which is already presenting (null)

请指导我如何使用Objective C正确使用UIAlertController。

谢谢，阿宾·科西·切里扬

Answer 1

我不知道你有什么问题，但你不应该那样做

handler:^(UIAlertAction * action)
                                       {
                                           [alert dismissViewControllerAnimated:YES completion:nil];

                                       }];

无论如何，它都会在你的任何actions上被驳回。