Issue while showing alert on window?

Question

I am setting root view controller of my app from below code

let navController = UINavigationController()
    //App Theming
    navController.navigationBar.barTintColor = Constant.AppColor.navigationColor
    navController.navigationBar.tintColor = Constant.AppColor.navigationBarTintColor
    navController.navigationBar.titleTextAttributes = [NSAttributedStringKey.foregroundColor: Constant.AppColor.navigationColorTextColor]
    navController.pushViewController(viewContoller, animated: true)
    let appDelegate = UIApplication.shared.delegate as! AppDelegate
    appDelegate.window?.rootViewController = navController
    appDelegate.window?.makeKeyAndVisible()

Now after I set one controller as root. Then I show alert on the window from below code.

    let window = UIApplication.shared.keyWindow!
     window.addSubView(mainView)

But the alert does not show up. please let me know what is the issue ? I am not able to understand .

EDIT: On app launch I call the api in app background thread so I get session expire & on session expire I am showing alert to user. So by the time alert is shown & new controller if navigated which hides the alert because new controller is crated .After that I try to show alert then it does not work

see this once may be it helps you https://stackoverflow.com/questions/36155769/how-to-show-uialertcontroller-from-appdelegate/36156077 — Anbu.Karthik, Mar 27 '18 at 06:31
Possible duplicate of [How to show UIAlertController from Appdelegate](https://stackoverflow.com/questions/36155769/how-to-show-uialertcontroller-from-appdelegate) — Vinaykrishnan, Mar 27 '18 at 06:36
Check my answer: [LINK](https://stackoverflow.com/a/49506453/4061501) — Lal Krishna, Mar 27 '18 at 07:12
Possible duplicate of [Present UIAlertController from AppDelegate](https://stackoverflow.com/questions/26952061/present-uialertcontroller-from-appdelegate) — Enea Dume, Mar 27 '18 at 08:12
@Techiee where did you put the above code? Is your alert a `UIAlertController` ? Where do you want to show it? — trungduc, Mar 30 '18 at 04:11
I am not using any UIAlertViewController. I am adding a custom view window & showing , hiding It with animation. — TechChain, Mar 30 '18 at 12:51
@Techiee Please make your question clearer and someone will give you a right answer. I don't know why you need `appDelegate.window?.rootViewController = navController` when showing alert and what is `mainView`? One more, where did you put the above code? — trungduc, Mar 31 '18 at 05:06

score 0 · Answer 1 · answered Mar 27 '18 at 06:38

0

Don't use window.addSubView(mainView) to show the alert.

Use a viewController that manages mainView and present it from the rootViewController.

See https://developer.apple.com/library/content/featuredarticles/ViewControllerPGforiPhoneOS/PresentingaViewController.html on how to present a viewController

answered Mar 27 '18 at 06:38

D. Mika

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I have made a custom class for this so I can't get the current controller object – TechChain Mar 27 '18 at 06:42
You want to present an alert from a custom class? This has been discussed a few times. (e.g.https://stackoverflow.com/questions/36155769/how-to-show-uialertcontroller-from-appdelegate) – D. Mika Mar 27 '18 at 06:46
Why do I need to create a new UIWindow() object every time I show an alert. I can use appdelegate window for that – TechChain Mar 27 '18 at 06:48
Normally an alert is displayed by a view controller and you can use the present method there. But if you are in a class that is not a ViewController or has no reference to a ViewController, things are more complicated. – D. Mika Mar 27 '18 at 06:52
I can't change the approach of showing the alert on view controller because I have reached so far in my code – TechChain Mar 27 '18 at 08:36
Than check then following https://stackoverflow.com/questions/26554894/how-to-present-uialertcontroller-when-not-in-a-view-controller – D. Mika Mar 27 '18 at 08:49

Madhu Dwivedi · Answer 2 · 2018-03-27T06:52:39.963

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First add root viewcontroller like this then add code for alert on viewdidappear in your view controller

let storyboard = UIStoryboard.init(name: "Main", bundle: nil)
let object  = storyboard.instantiateViewController(withIdentifier:"yourViewController") as! yourViewController            
let addNavi = UINavigationController(rootViewController: object)

self.window?.rootViewController = addNavi self.window?.makeKeyAndVisible()

edited Mar 27 '18 at 06:52

answered Mar 27 '18 at 06:41

Madhu Dwivedi

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` DispatchQueue.main.async { // add alert code }` – Madhu Dwivedi Mar 27 '18 at 07:03

score 0 · Answer 3 · edited Apr 04 '18 at 16:57

0

You can not show any alert on UIwindow, UINavigationController and on UItabbarController because these all are indicate to root.

You need to show on any UIViewcontroller object.

edited Apr 04 '18 at 16:57

msanford

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answered Apr 04 '18 at 12:04

sunil kumar

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Issue while showing alert on window?

3 Answers3