Handling back button presses

README.md

@@ -364,6 +364,26 @@ Several parameter keys have been pre-defined and are using by the `Burkus.Mvvm.M
 
 The `NavigationParameters` object exposes some handy properties `.UseAnimatedNavigation` and `.UseModalNavigation` so you can easily set or check the value of these properties.
 
+### Handling back button presses
+By default, back button presses on Android/Windows will bypass `Burkus.Mvvm.Maui` which would mean lifecycle events and parameter passing may not happen when you expect them to. You can allow `Burkus.Mvvm.Maui` to handle the back button navigation for a page by turning it into a `Burkus...Page`. For example, below a `ContentPage` is turned into a `BurkusContentPage`.
+
+``` xml
+<burkus:BurkusContentPage
+    ...
+    xmlns:burkus="http://burkus.co.uk"
+    ...>
+```
+
+``` csharp
+public partial class HomePage : BurkusContentPage
+```
+
+The page types available are:
+- `BurkusContentPage`
+- `BurkusNavigationPage`
+- `BurkusTabbedPage`
+- `BurkusFlyoutPage`
+
 ## Dialog service
 `IDialogService` is automatically registered by `.UseBurkusMvvm(...)`. It is a testable service that is an abstraction over [the MAUI alerts/pop-ups/prompts/action sheets](https://learn.microsoft.com/en-us/dotnet/maui/user-interface/pop-ups).
 

samples/DemoApp/MauiProgram.cs

@@ -4,6 +4,7 @@
 using DemoApp.ViewModels;
 using DemoApp.Views;
 using Microsoft.Extensions.Logging;
+using Microsoft.Maui.LifecycleEvents;
 
 namespace DemoApp;
 
@@ -23,11 +24,11 @@ public static MauiApp CreateMauiApp()
                     if (preferences.ContainsKey(PreferenceKeys.Username))
                     {
                         // we are logged in to the app
-                        await navigationService.Push<HomePage>();
+                        await navigationService.Navigate("/HomePage");
                     }
                     else
                     {
-                        await navigationService.Push<LoginPage>();
+                        await navigationService.Navigate("/LoginPage");
                     }
                 });
             })

samples/DemoApp/ViewModels/RegisterViewModel.cs

@@ -14,6 +14,11 @@ public RegisterViewModel(
 
     #endregion Constructors
 
+    public override async Task OnNavigatingFrom(NavigationParameters parameters)
+    {
+        await base.OnNavigatingFrom(parameters);
+    }
+
     #region Commands
 
     /// <summary>

samples/DemoApp/Views/ChangeUsernamePage.xaml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8" ?>
-<ContentPage
+<burkus:BurkusContentPage
     x:Class="DemoApp.Views.ChangeUsernamePage"
     xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
     xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
@@ -37,4 +37,4 @@
                 Text="{x:Static properties:Resources.Button_Finish}" />
         </Grid>
     </ScrollView>
-</ContentPage>
+</burkus:BurkusContentPage>

samples/DemoApp/Views/ChangeUsernamePage.xaml.cs

@@ -1,6 +1,6 @@
 namespace DemoApp.Views;
 
-public partial class ChangeUsernamePage : ContentPage
+public partial class ChangeUsernamePage : BurkusContentPage
 {
     public ChangeUsernamePage()
     {

samples/DemoApp/Views/Flyouts/ContactsPage.xaml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8" ?>
-<ContentPage
+<burkus:BurkusContentPage
     x:Class="DemoApp.Views.ContactsPage"
     xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
     xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
@@ -39,4 +39,4 @@
                 Text="{x:Static properties:Resources.Home_Button_TabbedPageDemo}" />
         </VerticalStackLayout>
     </ScrollView>
-</ContentPage>
+</burkus:BurkusContentPage>

samples/DemoApp/Views/Flyouts/ContactsPage.xaml.cs

@@ -1,6 +1,6 @@
 namespace DemoApp.Views;
 
-public partial class ContactsPage : ContentPage
+public partial class ContactsPage : BurkusContentPage
 {
     public ContactsPage()
     {

samples/DemoApp/Views/Flyouts/DemoFlyoutPage.xaml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8" ?>
-<FlyoutPage
+<burkus:BurkusFlyoutPage
     x:Class="DemoApp.Views.DemoFlyoutPage"
     xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
     xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
@@ -21,4 +21,4 @@
             </x:Arguments>
         </NavigationPage>
     </FlyoutPage.Detail>
-</FlyoutPage>
+</burkus:BurkusFlyoutPage>

samples/DemoApp/Views/Flyouts/DemoFlyoutPage.xaml.cs

@@ -1,6 +1,6 @@
 namespace DemoApp.Views;
 
-public partial class DemoFlyoutPage : FlyoutPage
+public partial class DemoFlyoutPage : BurkusFlyoutPage
 {
     public DemoFlyoutPage()
     {

samples/DemoApp/Views/Flyouts/RemindersPage.xaml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8" ?>
-<ContentPage
+<burkus:BurkusContentPage
     x:Class="DemoApp.Views.RemindersPage"
     xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
     xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
@@ -28,4 +28,4 @@
             </VerticalStackLayout>
         </ScrollView>
     </ScrollView>
-</ContentPage>
+</burkus:BurkusContentPage>

samples/DemoApp/Views/Flyouts/RemindersPage.xaml.cs

@@ -1,6 +1,6 @@
 namespace DemoApp.Views;
 
-public partial class RemindersPage : ContentPage
+public partial class RemindersPage : BurkusContentPage
 {
     public RemindersPage()
     {

samples/DemoApp/Views/Flyouts/TodoPage.xaml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8" ?>
-<ContentPage
+<burkus:BurkusContentPage
     x:Class="DemoApp.Views.TodoPage"
     xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
     xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
@@ -26,4 +26,4 @@
                 Text="{x:Static properties:Resources.Todo_Button_PushNewPageIntoDetail}" />
         </VerticalStackLayout>
     </ScrollView>
-</ContentPage>
+</burkus:BurkusContentPage>

samples/DemoApp/Views/Flyouts/TodoPage.xaml.cs

@@ -1,6 +1,6 @@
 namespace DemoApp.Views;
 
-public partial class TodoPage : ContentPage
+public partial class TodoPage : BurkusContentPage
 {
     public TodoPage()
     {

samples/DemoApp/Views/HomePage.xaml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8" ?>
-<ContentPage
+<burkus:BurkusContentPage
     x:Class="DemoApp.Views.HomePage"
     xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
     xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
@@ -67,4 +67,4 @@
                 Text="{x:Static properties:Resources.Home_Button_FlyoutPageDemo}" />
         </VerticalStackLayout>
     </ScrollView>
-</ContentPage>
+</burkus:BurkusContentPage>

samples/DemoApp/Views/HomePage.xaml.cs

@@ -1,6 +1,6 @@
 namespace DemoApp.Views;
 
-public partial class HomePage : ContentPage
+public partial class HomePage : BurkusContentPage
 {
     public HomePage()
     {

samples/DemoApp/Views/LoginPage.xaml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8" ?>
-<ContentPage
+<burkus:BurkusContentPage
     x:Class="DemoApp.Views.LoginPage"
     xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
     xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
@@ -54,4 +54,4 @@
             </Label>
         </Grid>
     </ScrollView>
-</ContentPage>
+</burkus:BurkusContentPage>

samples/DemoApp/Views/LoginPage.xaml.cs

@@ -1,6 +1,6 @@
 namespace DemoApp.Views;
 
-public partial class LoginPage : ContentPage
+public partial class LoginPage : BurkusContentPage
 {
     public LoginPage()
     {

samples/DemoApp/Views/RegisterPage.xaml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8" ?>
-<ContentPage
+<burkus:BurkusContentPage
     x:Class="DemoApp.Views.RegisterPage"
     xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
     xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
@@ -30,4 +30,4 @@
                 Text="{x:Static properties:Resources.Button_GoBack}" />
         </Grid>
     </ScrollView>
-</ContentPage>
+</burkus:BurkusContentPage>

samples/DemoApp/Views/RegisterPage.xaml.cs

@@ -1,6 +1,6 @@
 namespace DemoApp.Views;
 
-public partial class RegisterPage : ContentPage
+public partial class RegisterPage : BurkusContentPage
 {
     public RegisterPage()
     {

samples/DemoApp/Views/Tabs/AlphaTabPage.xaml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8" ?>
-<ContentPage
+<burkus:BurkusContentPage
     x:Class="DemoApp.Views.AlphaTabPage"
     xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
     xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
@@ -35,4 +35,4 @@
                 Text="{x:Static properties:Resources.Button_GoBack}" />
         </Grid>
     </ScrollView>
-</ContentPage>
+</burkus:BurkusContentPage>

samples/DemoApp/Views/Tabs/AlphaTabPage.xaml.cs

@@ -1,6 +1,6 @@
 namespace DemoApp.Views;
 
-public partial class AlphaTabPage : ContentPage
+public partial class AlphaTabPage : BurkusContentPage
 {
     public AlphaTabPage()
     {

samples/DemoApp/Views/Tabs/BetaTabPage.xaml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8" ?>
-<ContentPage
+<burkus:BurkusContentPage
     x:Class="DemoApp.Views.BetaTabPage"
     xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
     xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
@@ -35,4 +35,4 @@
                 Text="{x:Static properties:Resources.Button_GoBack}" />
         </Grid>
     </ScrollView>
-</ContentPage>
+</burkus:BurkusContentPage>

samples/DemoApp/Views/Tabs/BetaTabPage.xaml.cs

@@ -1,6 +1,6 @@
 namespace DemoApp.Views;
 
-public partial class BetaTabPage : ContentPage
+public partial class BetaTabPage : BurkusContentPage
 {
     public BetaTabPage()
     {

samples/DemoApp/Views/Tabs/CharlieTabPage.xaml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8" ?>
-<ContentPage
+<burkus:BurkusContentPage
     x:Class="DemoApp.Views.CharlieTabPage"
     xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
     xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
@@ -35,4 +35,4 @@
                 Text="{x:Static properties:Resources.Button_GoBack}" />
         </Grid>
     </ScrollView>
-</ContentPage>
+</burkus:BurkusContentPage>

samples/DemoApp/Views/Tabs/CharlieTabPage.xaml.cs

@@ -1,6 +1,6 @@
 namespace DemoApp.Views;
 
-public partial class CharlieTabPage : ContentPage
+public partial class CharlieTabPage : BurkusContentPage
 {
     public CharlieTabPage()
     {

samples/DemoApp/Views/Tabs/DemoTabsPage.xaml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8" ?>
-<TabbedPage
+<burkus:BurkusTabbedPage
     x:Class="DemoApp.Views.DemoTabsPage"
     xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
     xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
@@ -13,4 +13,4 @@
     <views:AlphaTabPage Title="Alpha" />
     <views:BetaTabPage Title="Beta" />
     <views:CharlieTabPage Title="Charlie" />
-</TabbedPage>
+</burkus:BurkusTabbedPage>

samples/DemoApp/Views/Tabs/DemoTabsPage.xaml.cs

@@ -1,6 +1,6 @@
 namespace DemoApp.Views;
 
-public partial class DemoTabsPage : TabbedPage
+public partial class DemoTabsPage : BurkusTabbedPage
 {
     public DemoTabsPage()
     {

samples/DemoApp/Views/UriTestPage.xaml

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8" ?>
-<ContentPage
+<burkus:BurkusContentPage
     x:Class="DemoApp.Views.UriTestPage"
     xmlns="http://schemas.microsoft.com/dotnet/2021/maui"
     xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
@@ -48,4 +48,4 @@
                 Text="{x:Static properties:Resources.UriTest_Button_SwitchToChangeUsername}" />
         </VerticalStackLayout>
     </ScrollView>
-</ContentPage>
+</burkus:BurkusContentPage>

samples/DemoApp/Views/UriTestPage.xaml.cs

@@ -1,6 +1,6 @@
 namespace DemoApp.Views;
 
-public partial class UriTestPage : ContentPage
+public partial class UriTestPage : BurkusContentPage
 {
     public UriTestPage()
     {

src/Burkus.Mvvm.Maui/Models/Pages/BackButtonNavigator.cs

@@ -0,0 +1,14 @@
+namespace Burkus.Mvvm.Maui;
+
+internal static class BackButtonNavigator
+{
+    internal static bool HandleBackButtonPressed()
+    {
+        var navigationService = ServiceResolver.Resolve<INavigationService>();
+
+        _ = navigationService.Pop();
+
+        // On Android and Windows, prevent the default back button behaviour
+        return true;
+    }
+}

src/Burkus.Mvvm.Maui/Models/Pages/BurkusContentPage.cs

@@ -0,0 +1,9 @@
+namespace Burkus.Mvvm.Maui;
+
+public class BurkusContentPage : ContentPage
+{
+    protected override bool OnBackButtonPressed()
+    {
+        return BackButtonNavigator.HandleBackButtonPressed();
+    }
+}

src/Burkus.Mvvm.Maui/Models/Pages/BurkusFlyoutPage.cs

@@ -0,0 +1,9 @@
+namespace Burkus.Mvvm.Maui;
+
+public class BurkusFlyoutPage : FlyoutPage
+{
+    protected override bool OnBackButtonPressed()
+    {
+        return BackButtonNavigator.HandleBackButtonPressed();
+    }
+}