如何从appDelegate展示UIAlertView

我试图显示从应用程序收到推送通知时didReceiveRemoteNotification appDelegate UIAlertView。

我有这个错误：

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

这里是我的代码：

 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

要使用Objective-C从AppDelegate生成AlertController对话框，

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

types1

 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]; 

types2

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

两者都testing和工作正常。

Answer 2

好吧，我终于明白了，你需要在尝试呈现你的alertController之前使用它来find活动的VC：

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

Answer 3

我是怎么做到的

 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) } 

使用示例

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

下载源代码示例

Answer 4

如果你在Objective-C中需要相同的话

 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]; 

1. 如果你有导航的应用程序：

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

2. 如果您有单一视图的应用程序：

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

Answer 5

这里是我的Swift 3.0例子

 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) } 

希望有助于某人

Answer 6

从应用程序委托显示顶部控制器上的警报

 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) 

在UIAlertController中添加扩展

  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) } 

Answer 7

我使用UIViewController扩展来获取当前可见的视图控制器（请参阅： 如何使用故事板从应用程序委托获取可见的viewController？ ）。

然后提出警报控制器：

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