How to present UIAlertView from appDelegate

Question

I m trying to display a UIAlertView from the appDelegate in didReceiveRemoteNotification when the app receive a push notification.

I ve this error :

  Warning: Attempt to present <UIAlertController: 0x14c5494c0> on <UINavigationController:
  0x14c60ce00> whose view is not in the window hierarchy!

here is my code :

func application(application: UIApplication, didReceiveRemoteNotification userInfo: NSDictionary) {

    var contentPush: NSDictionary = userInfo.objectForKey("aps") as NSDictionary

    var message = contentPush.objectForKey("alert") as String



    let alertController = UIAlertController(title: "Default Style", message: message, preferredStyle: .Alert)

    let cancelAction = UIAlertAction(title: "Cancel", style: .Cancel) { (action) in
                    // ...
    }
    alertController.addAction(cancelAction)

    let OKAction = UIAlertAction(title: "OK", style: .Default) { (action) in

        let photoPushedVc = self.storyboard.instantiateViewControllerWithIdentifier("CommentTableViewController") as CommentTableViewController

        println("the fetched post is \(post)")

        photoPushedVc.post = post

        let activeVc = UIApplication.sharedApplication().keyWindow?.rootViewController

        activeVc?.presentViewController(photoPushedVc, animated: true, completion: nil)
   }

   alertController.addAction(OKAction)

   let activeVc = UIApplication.sharedApplication().keyWindow?.rootViewController


   activeVc?.presentViewController(alertController, animated: true, completion: nil)}

Are you trying to have it display from the root view controller? — Lyndsey Scott, Jan 06 '15 at 21:03
as you can see in my code, i m trying to dysplay it from the active VC using let activeVc = UIApplication.sharedApplication().keyWindow?.rootViewController — jmcastel, Jan 06 '15 at 21:05
Why would you think a "rootViewController" is necessarily the "active VC"? — Lyndsey Scott, Jan 06 '15 at 21:36
i was thinking that the .keyWindow? gives the "active VC". If not how would you get it ? — jmcastel, Jan 06 '15 at 21:38
Yes i do. Found this http://stackoverflow.com/questions/9009646/current-view-controller-from-appdelegate but can't translate in swift. — jmcastel, Jan 06 '15 at 21:45
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/68306/discussion-between-jmcastel-and-lyndsey-scott). — jmcastel, Jan 06 '15 at 22:48

score 20 · Answer 1 · answered Jun 29 '16 at 01:37

To generate AlertController Dialog Box from AppDelegate using Objective-C,

UIAlertController *alertController = [UIAlertController alertControllerWithTitle:@"Title" message:@"Hello World!" preferredStyle:UIAlertControllerStyleAlert];
UIAlertAction* ok = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:nil];
[alertController addAction:ok];

Type 1

UIWindow *alertWindow = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds];
alertWindow.rootViewController = [[UIViewController alloc] init];
alertWindow.windowLevel = UIWindowLevelAlert + 1;
[alertWindow makeKeyAndVisible];
[alertWindow.rootViewController presentViewController:alertController animated:YES completion:nil];

Type 2

UIViewController *topController = [UIApplication sharedApplication].keyWindow.rootViewController;
while (topController.presentedViewController) {
    topController = topController.presentedViewController;
}
[topController presentViewController:alertController animated:YES completion:nil];

Both are tested and working fine.

Type 1 worked for any case. Type 2 may not work for some of devices. — Manish, Nov 13 '19 at 06:07

score 13 · Accepted Answer · edited Jun 07 '18 at 05:24

13

Ok i finally got it, you need to find the active VC using this before trying to present your alertController :

let navigationController = application.windows[0].rootViewController as UINavigationController
let activeViewCont = navigationController.visibleViewController
activeViewCont.presentViewController(alertController, animated: true, completion: nil)

edited Jun 07 '18 at 05:24

cjohnson318

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answered Jan 07 '15 at 09:34

jmcastel

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1

You should also check that activeVC is not already presenting, otherwise it won't works. By checking if activeViewCont.presentedViewController return nil – Lory Huz Dec 17 '15 at 13:17

score 13 · Answer 3 · answered Mar 21 '17 at 23:20

13

Here is mine Swift 3.0 example

func showTopLevelAlert() {
    let alertController = UIAlertController (title: "title", message: "message.", preferredStyle: .alert)

    let firstAction = UIAlertAction(title: "First", style: .default, handler: nil)
    alertController.addAction(firstAction)

    let cancelAction = UIAlertAction(title: "Отмена", style: .cancel, handler: nil)
    alertController.addAction(cancelAction)

    let alertWindow = UIWindow(frame: UIScreen.main.bounds)

    alertWindow.rootViewController = UIViewController()
    alertWindow.windowLevel = UIWindowLevelAlert + 1;
    alertWindow.makeKeyAndVisible()

    alertWindow.rootViewController?.present(alertController, animated: true, completion: nil)

}

Hope it helps to someone

answered Mar 21 '17 at 23:20

Nosov Pavel

1,571
1
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This looks like a good one. Just one reminder: Don't forget to do all of this inside the main thread, otherwise it will crash at `alertWindow.makeKeyAndVisible()`. – Guven Mar 23 '18 at 14:12
How will the `UIWindow` be deallocated? – meaning-matters Jul 10 '18 at 20:14
@meaning-matters it will be deallocated as you close UIAlertController dialog – Nosov Pavel Jul 10 '18 at 21:55

umakanta · Answer 4 · 2016-03-30T08:34:08.840

If you need the same in Objective-c

UIAlertController *alertvc = [UIAlertController alertControllerWithTitle:@"Alert Title..!!" message:@"Hey! Alert body come here." preferredStyle:UIAlertControllerStyleAlert];
UIAlertAction *actionOk = [UIAlertAction actionWithTitle:@"OK" style:UIAlertActionStyleDefault handler:^(UIAlertAction * _Nonnull action) {

}];

[alertvc addAction:actionOk];

If you have navigation based app:

UINavigationController *nvc = (UINavigationController *)[[application windows] objectAtIndex:0].rootViewController;
UIViewController *vc = nvc.visibleViewController;
[vc presentViewController:alertvc animated:YES completion:nil];

If you have single view based app:

UIViewController *vc = self.window.rootViewController;
[vc presentViewController:alertvc animated:YES completion:nil];

How do you do this with a single view app (not a navigation controller based app). — Supertecnoboff, Mar 27 '16 at 09:35
@Supertecnoboff Please check my second answer. (Answer updated.) — umakanta, Mar 30 '16 at 08:37

score 5 · Answer 5 · edited Oct 31 '18 at 21:35

how i did it

func showAlertAppDelegate(title : String,message : String,buttonTitle : String,window: UIWindow){
    let alert = UIAlertController(title: title, message: message, preferredStyle: UIAlertControllerStyle.Alert)
    alert.addAction(UIAlertAction(title: buttonTitle, style: UIAlertActionStyle.Default, handler: nil))
    window.rootViewController?.presentViewController(alert, animated: true, completion: nil)
}

Use Example

self.showAlertAppDelegate(title: "Alert",message: "Opened From AppDelegate",buttonTitle: "ok",window: self.window!);

Download Example With Source Code

score 1 · Answer 6 · answered Jul 21 '17 at 03:51

I use an UIViewController extension to get the current visible view controller (see: How to get visible viewController from app delegate when using storyboard?).

and then present the alert controller:

let visibleVC = UIApplication.sharedApplication().keyWindow?.rootViewController?.visibleViewController
visibleVC!.presentViewController(alertController, animated: true, completion: nil)

score 0 · Answer 7 · answered Mar 08 '17 at 10:43

To show alert on top controller from app delegate

var topController : UIViewController = (application.keyWindow?.rootViewController)!

    while ((topController.presentedViewController) != nil) {
        topController = topController.presentedViewController!
    }

    //showAlertInViewController func is in UIAlertController Extension
    UIAlertController.showAlertInViewController(topController, withMessage: messageString, title: titleString)

Add extension in UIAlertController

    static func showAlertInViewController(viewController: UIViewController?, withMessage message: String, title: String) {
    let myAlert = UIAlertController(title: title, message: message, preferredStyle: UIAlertControllerStyle.Alert)

    myAlert.addAction(UIAlertAction(title: NSLocalizedString("Ok", comment: ""), style: .Default, handler: { (action: UIAlertAction!) in
        print("Handle Ok logic here")

        // Let the alert simply dismiss for now
    }))

    viewController?.presentViewController(myAlert, animated: true, completion: nil)
}

How to present UIAlertView from appDelegate

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