So zeigen Sie UIAlertController von Appdelegate

Question

Ich arbeite mit PushNotification auf iOS App. Ich möchte einen UIalertcontroller zeigen, wenn die App eine Benachrichtigung erhält.

Ich versuche, diesen Code in der unten stehenden AppDelegate:

[self.window.rootViewController presentViewController:alert animated:YES completion:nil]; 

Aber die UIAlertcontroller im Stammansicht (Erster Bildschirm) und für andere Uiviewcontroller zeigt i bekam Warnung oder die App stürzt ab.

Answer 1

versuchen, diese

Objective-C

UIWindow* topWindow = [[UIWindow alloc] initWithFrame:[UIScreen mainScreen].bounds]; 
topWindow.rootViewController = [UIViewController new]; 
topWindow.windowLevel = UIWindowLevelAlert + 1; 

UIAlertController* alert = [UIAlertController alertControllerWithTitle:@"APNS" message:@"received Notification" preferredStyle:UIAlertControllerStyleAlert]; 

[alert addAction:[UIAlertAction actionWithTitle:NSLocalizedString(@"OK",@"confirm") style:UIAlertActionStyleCancel handler:^(UIAlertAction * _Nonnull action) { 
    // continue your work 

// important to hide the window after work completed. 
// this also keeps a reference to the window until the action is invoked. 
topWindow.hidden = YES; 
}]]; 

[topWindow makeKeyAndVisible]; 
[topWindow.rootViewController presentViewController:alert animated:YES completion:nil]; 

swift3

let topWindow = UIWindow(frame: UIScreen.main.bounds) 
topWindow.rootViewController = UIViewController() 
topWindow.windowLevel = UIWindowLevelAlert + 1 
let alert = UIAlertController(title: "APNS", message: "received Notification", preferredStyle: .alert) 
alert.addAction(UIAlertAction(title: NSLocalizedString("OK", comment: "confirm"), style: .cancel, handler: {(_ action: UIAlertAction) -> Void in 
    // continue your work 
    // important to hide the window after work completed. 
    // this also keeps a reference to the window until the action is invoked. 
    topWindow.isHidden = true 
})) 
topWindow.makeKeyAndVisible() 
topWindow.rootViewController?.present(alert, animated: true, completion: { _ in }) 

Swift

var topWindow: UIWindow = UIWindow(frame: UIScreen.mainScreen().bounds) 
topWindow.rootViewController = UIViewController() 
topWindow.windowLevel = UIWindowLevelAlert + 1 
var alert: UIAlertController = UIAlertController.alertControllerWithTitle("APNS", message: "received Notification", preferredStyle: .Alert) 
alert.addAction(UIAlertAction.actionWithTitle(NSLocalizedString("OK", "confirm"), style: .Cancel, handler: {(action: UIAlertAction) -> Void in 
// continue your work 
// important to hide the window after work completed. 
// this also keeps a reference to the window until the action is invoked. 
topWindow.hidden = true 
})) 
topWindow.makeKeyAndVisible() 
topWindow.rootViewController.presentViewController(alert, animated: true, completion: { _ in }) 

Detailbeschreibung: http://www.thecave.com/2015/09/28/how-to-present-an-alert-view-using-uialertcontroller-when-you-dont-have-a-view-controller/