MAUI DisplayAlert() When User Closes Window : Getting Unhandled Exception

Question

I want to show an ALERT/POPUP to the user to ask him/her before he closes the Application.

This is what I am already doing :

In App.xaml.cs

Application.Current.MainPage.DisplayAlert this line throws unhandled exception,

The Exception gets unhandled by debugger itself. and it says :

a debugger is attached to but not configured to debug this unhandled exception.

https://github.com/BhangeeF16/MAUI-DOT-NET/blob/main/SampleApp/App.xaml.cs

public partial class App : Application
{
    public static IServiceProvider Services;

    public App(IServiceProvider serviceProvider)
    {
        InitializeComponent();
        Services = serviceProvider;
        MainPage = new MainPage();
    }
    protected override Window CreateWindow(IActivationState activationState)
    {
        Window window = base.CreateWindow(activationState);
        window.Page = MainPage;
        window.Destroying += Window_Destroying;
        return window;
    }

    private void Window_Destroying(object sender, EventArgs e)
    {
        try
        {
            System.Diagnostics.Debug.WriteLine("Destroying");
            App.Current.Dispatcher.Dispatch(async () =>
            await App.Current.MainPage.DisplayAlert("Alert", "Are you sure you want to close the application.", "Yes", "No"));    
        }
        catch (Exception)
        {
        }
    }
}

https://learn.microsoft.com/en-us/dotnet/maui/fundamentals/app-lifecycle — monstertjie_za, Aug 11 '22 at 10:16
I read the documentation, implemented an override for it, the issue now is that I cant get the alert to show. @monstertjie_za — BNG016, Aug 11 '22 at 10:59
It's impossible to pop up an alert from a closed window, the handle will not be valid. Please be noted that `the destroy event` is for releasing resources. — Alexandar May - MSFT, Aug 17 '22 at 02:13

score 1 · Answer 1 · answered Aug 11 '22 at 10:15

1

I would suggest you read and understand the life cycle of an MAUI app: Docs

The event you are looking for should either be OnStopped, or OnDestroying, dependant on your needs.

answered Aug 11 '22 at 10:15

monstertjie_za

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I read the documentation, implemented an override for it, the issue now is that I cant get the alert to show. Every time I try to show an Alert it throws an exception @monstertjie_za – BNG016 Aug 11 '22 at 11:07

MAUI DisplayAlert() When User Closes Window : Getting Unhandled Exception

1 Answers1