BackPress pop up option to just before closing the application in .NET Maui blazor

Question

In my .NET Maui hybrid application using Blazor, I have a requirement: when a user attempts to navigate back or presses the back button in the mobile app, I need to display a confirmation popup asking if they want to close the application before proceeding to close the app. I tried below code in App.xaml.cs, but its showing pop up when opening the application again. I want to know which method to be called just before closing the application.

 public partial class App : Application
 {
     private IAudioPlayer _audioPlayer;
     private IAudioManager _audioManager;
     private NavigationManager NavigationManager;
     public bool isPlaying = true;
     public App(IAudioManager audioManager)
     {
         InitializeComponent();
         MainPage = new MainPage();
         _audioManager = audioManager;
     }
     protected override Window CreateWindow(IActivationState? activationState)
     {
         Window window = base.CreateWindow(activationState);

         window.Created += (s, e) =>
         {
             // Custom logic
         };

         window.Destroying += (s, e) =>
         {
             _audioPlayer.Stop();
         };

         window.Deactivated += (s, e) =>
         {
             if (_audioPlayer != null)
             {
                 _audioPlayer.Stop();
             }
         };
         
         window.Deactivated += Window_Deactivated;
        
         return window;

     
     }

  }

private async void Window_Deactivated(object sender, EventArgs e) { bool canDeactivate = await ShowConfirmationDialog(); if (!canDeactivate) {

        }
    }

    private async Task<bool> ShowConfirmationDialog()
    {
        bool canDeactivate = false;
        string message = "Do you want to leave the app?";
        var result = await MainPage.DisplayAlert("Confirmation", message, "Yes", "No");
        if (result)
        {
            canDeactivate = true;
        }
        return canDeactivate;
    }

I tried to do something like this in App.xaml.cs but with after closing the app it calling so that opening again my pop is showing.

Answer 1

According to this post https://learn.microsoft.com/en-us/answers/questions/1118583/how-to-alerts-user-when-tap-exit-maui-android The following code inserted in the MainPage.xaml.cs file

protected  override   bool OnBackButtonPressed()  
   {  
        
       Task<bool> answer =  DisplayAlert("Question?", "Do you want to exit?", "Yes", "No");  
       answer.ContinueWith(task =>  
       {  
          if (task.Result)  
           {  
               Application.Current.Quit();  
           }  
       });         
       return true;  
   }  

will do as you asked. From my testing it works

Answer 2

On Android platform, if the MainPage is your root page, you can try to set Popup when you click the back button by override the OnBackButtonPressed method in MainPage.xaml.cs:

protected override  bool OnBackButtonPressed()
{
    Dispatcher.Dispatch(async () =>
    {
        var leave = await DisplayAlert("asd", "dsadsa", "Yes", "No");
        if (leave)
        {
            Exit();
        }
    });
    return false;
}​

//This method is used to move the application to the background
public void Exit()
{
    bool exit = Microsoft.Maui.ApplicationModel.Platform.CurrentActivity.MoveTaskToBack(true);
    if (!exit)
    {
        var intent = new Android.Content.Intent(Android.Content.Intent.ActionMain);
        intent.AddCategory(Android.Content.Intent.CategoryHome);
        Microsoft.Maui.ApplicationModel.Platform.CurrentActivity.StartActivity(intent);
    }
}