从AppDelegate展示UIAlertController [英] Present UIAlertController from AppDelegate

问题描述

我正试图在我的iOS应用程序中从AppDelegate呈现 UIAlertController 。
以下是警报和现在的方法。

I'm trying to present a UIAlertController from the AppDelegate in my iOS app. Below is the alert and the present method.

UIAlertController *alert = [UIAlertController alertControllerWithTitle:cTitle message:cMessage preferredStyle:UIAlertControllerStyleAlert];

//Configure alert and actions

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

但是，当我尝试提示警报时，它不会出现，我收到以下警报在控制台中。

However, when I try to present the alert, it doesn't appear and I get the following alert in the console.

Warning: Attempt to present <UIAlertController: 0x145f5d60> on <UINavigationController: 0x146590f0> whose view is not in the window hierarchy!

导致错误的原因是什么以及如何解决？

What is causing the error and how do I fix it?

推荐答案

如果你想从didFinishLaunchingWithOptions.Hope启动它，也可以使用这段代码。这有帮助。

You can use this code as well if you want to launch it from didFinishLaunchingWithOptions.Hope this helps.

dispatch_async(dispatch_get_main_queue(), {
              let importantAlert: UIAlertController = UIAlertController(title: "Action Sheet", message: "Hello I was presented from appdelegate ;)", preferredStyle: .ActionSheet)
            self.window?.rootViewController?.presentViewController(importantAlert, animated: true, completion: nil)
        })

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