When using NavigationPage as the main page, I do not receive back button events.

Question

Hi, in App.xaml.cscs I have my main page initiated like this:

MainPage = new NavigationPage(new MainPage());

However when I do that, this event is never called from any of my pages:

protected override bool OnBackButtonPressed()

If I use

 AppShell();

Then teh back button event works. However I am not able to use AppShell for other reasons.

How do I capture the OnBackButtonPressed() event?

Answer 1

Hello,

Based on your previous link, you implement OnBackButtonPressed in iOS on the latest Maui.

I can reproduce this issue. Here is a solution, you can create a CustomNavigationPageRenderer in MauiAppproject/Platforms/iOS folder, then overrider PopViewController and get the current page, if the back button pressed, this PopViewController will be executed, get current page and invoke SendBackButtonPressed. If the value is true, do not execute back to the previous page. If false, you can back to the previous page.

using Microsoft.Maui.Controls.Handlers.Compatibility;
using UIKit;
 
namespace MauiApp2.Platforms.iOS
{
    public class CustomNavigationPageRenderer : NavigationRenderer
    {
        public override UIViewController PopViewController(bool animated)
        {
            if (Element is NavigationPage navigationPage)
            {
                var currentPage = navigationPage.Navigation.NavigationStack.LastOrDefault();
                if (currentPage != null)
                {
                    // Invoke the back button pressed logic
                    var handled = currentPage.SendBackButtonPressed();
 
                    if (handled)
                    {
                        // If the back button press was handled, cancel the default behavior
                        return null;
                    }
                }
            }
 
            // Proceed with the default back navigation
            return base.PopViewController(animated);
        }
    }
}

After that, you can reigster this CustomNavigationPageRenderer in the MauiProgram.cs for iOS platform.

public static class MauiProgram
    {
        public static MauiApp CreateMauiApp()
        {
            var builder = MauiApp.CreateBuilder();
            builder
                .UseMauiApp<App>()
                .ConfigureFonts(fonts =>
                {
                    fonts.AddFont("OpenSans-Regular.ttf", "OpenSansRegular");
                    fonts.AddFont("OpenSans-Semibold.ttf", "OpenSansSemibold");
                })
                .ConfigureMauiHandlers((handlers) =>
                {
#if  IOS
                    handlers.AddHandler(typeof(NavigationPage), typeof(MauiApp2.Platforms.iOS.CustomNavigationPageRenderer));
#endif
                });

...

In the end, you can add OnBackButtonPressed in your detailed page.

  protected override bool OnBackButtonPressed()
   {
       //handle your operation
       return true;
   }

Best Regards,

Leon Lu

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