App.xaml.cs

using ToDoListApp.Views;
using Microsoft.Maui.Controls;
using Plugin.Maui.Biometric;
using static ToDoListApp.ToastService;
#if IOS
using WebKit;
#endif

namespace ToDoListApp;

public partial class App : Application
{
    public App()
    {
        InitializeComponent();
        // Register routes for navigation
        Routing.RegisterRoute(nameof(Dashboard), typeof(Dashboard));
        Routing.RegisterRoute(nameof(Welcome), typeof(Welcome));
        Routing.RegisterRoute(nameof(AppLockedPage), typeof(AppLockedPage));
        

        MainPage = new AppShell();

        MainPage.Dispatcher.Dispatch(async () =>
        {
            bool isBiometricsEnabled = Preferences.Get("BiometricsEnabled", false);

            if (Preferences.ContainsKey("IsFirstRun"))
            {
                MainPage = new AppShell();
            }
            else
            {
                // Navigate to the Welcome page and set the first-run preference
                await MainPage.Navigation.PushAsync(new Welcome());
                Preferences.Set("IsFirstRun", true);
            }

            if (isBiometricsEnabled)
            {
                await MainPage.Navigation.PushAsync(new AppLockedPage());
            }
        });
    }

    protected override async void OnResume()
    {
        base.OnResume();

#if ANDROID
        await Task.Delay(500); // Android needs this delay or authentication will be bypassed
#endif

        bool isBiometricsEnabled = Preferences.Get("BiometricsEnabled", false);

        if (isBiometricsEnabled == true)
        {
            // Biometric authentication
            var biometric = await BiometricAuthenticationService.Default.AuthenticateAsync(new AuthenticationRequest()
            {
                Title = "Authenticate",
                Subtitle = "Please authenticate to access the app",
                Description = "Please use your biometric to authenticate",
                NegativeText = "Cancel",
                AuthStrength = AuthenticatorStrength.Weak,
                AllowPasswordAuth = true

            }, CancellationToken.None);

            if (biometric.Status == BiometricResponseStatus.Failure)
            {
                await MainPage.Navigation.PushAsync(new AppLockedPage());
            }
        }
    }
}