Presenting Alert Controller from the delegate

Question

In context of this question/answer I've attempted but the result is no alert presented.

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
    // Override point for customization after application launch.
    
    
    let alertController = UIAlertController(title: "Error", message: "ABc", preferredStyle: UIAlertController.Style.alert)
    alertController.addAction(UIAlertAction(title: "OK", style: UIAlertAction.Style.default, handler: nil))
    
    let win = UIWindow(frame: UIScreen.main.bounds)
    let vc = UIViewController()
    vc.view.backgroundColor = .clear
    win.rootViewController = vc
    win.windowLevel = UIWindow.Level.alert + 1  // Swift 3-4: UIWindowLevelAlert + 1
    win.makeKeyAndVisible()
    vc.present(alertController, animated: true, completion: nil)

    return true
}

Attempt 2 based on the answer.

I'm running some pre-startup related stuff before the app loads, I need to present an alert message in case any issues appear. Any solution? — AppDeveloper, Nov 30 '20 at 04:18
The solution is to present it in the first view controller after it loads. — cora, Nov 30 '20 at 14:10
@cora code snippet please, I tried the answer below but `self.window` is nil to begin with — AppDeveloper, Dec 06 '20 at 10:44

Virani Vivek · Accepted Answer · 2020-12-10T08:44:20.760

2

Use below line:

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

Instead of

vc.present(alertController, animated: true, completion: nil)

than problem is solved.

Example:

DispatchQueue.main.asyncAfter(deadline: DispatchTime.now() + 0.5, execute: {
        let alertController = UIAlertController(title: "Alert Title", message:
          "Message", preferredStyle: .actionSheet)

        let okAction = UIAlertAction(title: "Ok", style:.default) {
            UIAlertAction in
            NSLog("OK Pressed")
        }

        let cancelAction = UIAlertAction(title: "Cancel", style: .cancel) {
            UIAlertAction in
            NSLog("Cancel Pressed")
        }

        alertController.addAction(okAction)
        alertController.addAction(cancelAction)
        self.window?.rootViewController?.present(alertController, animated: true, completion: nil)
    })

edited Dec 10 '20 at 08:44

answered Nov 30 '20 at 04:35

Virani Vivek

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`self.window` is nil within `didFinishLaunchingWithOptions` method – AppDeveloper Dec 06 '20 at 10:43
Hello, can you please try your answer and post a working example? – AppDeveloper Dec 10 '20 at 07:03
@AppDeveloper please see my updated answer – Virani Vivek Dec 10 '20 at 07:13
1

No its not working, https://i.stack.imgur.com/i5raz.png, you have a compilation error as well, please test the code. – AppDeveloper Dec 10 '20 at 08:35
sorry to say, nops, https://i.stack.imgur.com/GpnGV.png increased delay as well, I'm using navigation controller as initial view contorller in my app, is that the difference? Can you please post a screenshot from your end? – AppDeveloper Dec 10 '20 at 08:51
ok will upload if yo're using a navigationController. – Virani Vivek Dec 10 '20 at 08:53
Let us [continue this discussion in chat](https://chat.stackoverflow.com/rooms/225767/discussion-between-virani-vivek-and-appdeveloper). – Virani Vivek Dec 10 '20 at 08:54

Presenting Alert Controller from the delegate

1 Answers1