How to present UIAlertView from appDelegate - ios

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)}

Answer 1

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.

Answer 2

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)

Answer 3

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

Answer 4

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];

Answer 5

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

Answer 6

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)

Answer 7

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)
}