如何在呈现控制器的顶部显示 UIAlertController

Question

我有顶视图控制器正在显示，我想显示警报控制器但它没有显示。有什么办法吗？

var appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
appDelegate.window?.rootViewController?.presentViewController(alert, animated: true, completion: nil)

Answer 1

检查这个：

func showAlert() {
    let alert = UIAlertController(title: "Title", message: "Message", preferredStyle: UIAlertControllerStyle.Alert)

    let yesAction = UIAlertAction(title: "YES", style: UIAlertActionStyle.Default) { (action: UIAlertAction!) -> Void in
        print("YES tapped")
    }
    let cancelAction = UIAlertAction(title: "Cancel", style: UIAlertActionStyle.Cancel) { (action: UIAlertAction!) -> Void in
        print("Cancel tapped")
    }

    alert.addAction(yesAction)
    alert.addAction(cancelAction)

    var appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
    appDelegate.window?.rootViewController?.presentViewController(alert, animated: true, completion: nil)
}

还请检查并确保您的 rootViewController 不为零。

Answer 2

终于解决了我的问题。很简单，只需将我们站立的控制器输入下面的 show alertcontroller 函数即可：

func showAlerControler(title: String?, message: String, confirmButtonText: String?, cancelButtonText: String?, atController: UIViewController){
    var alert: UIAlertController = UIAlertController(title: title, message: message, preferredStyle: .Alert)
    if let confirmStr = confirmButtonText{
    alert.addAction(UIAlertAction(title: confirmStr, style: .Default, handler: { (ACTION) -> Void in

    }))
    }
    if let cancelStr = cancelButtonText{
        alert.addAction(UIAlertAction(title: cancelStr, style: .Default, handler: { (ACTION) -> Void in

        }))
    }
    atController.presentViewController(alert, animated: true, completion: nil)
}

不要使用appDelegate.window?.rootViewController?.presentViewController(alert, animated: true, completion: nil)

并且你可以站在任何控制器上调用showAlerControler并输入atController是self

Answer 3

(Objective-C)

UIAlertController *alertVC = [UIAlertController
                                          alertControllerWithTitle:@"myTitle" message:@"myMessage"
                                          preferredStyle:UIAlertControllerStyleAlert];
[alertVC addAction:[UIAlertAction
                        actionWithTitle:@"Ok"
                        style:UIAlertActionStyleDefault
                        handler:^(UIAlertAction* action) {
                            [alertVC dismissViewControllerAnimated:YES completion:nil];
                        }
    ]];
[self presentViewController:alertVC animated:YES completion:nil];

如何在呈现控制器的顶部显示 UIAlertController

How to show UIAlertController top of the presenting cotroller

objective-c

ios

swift

ios8