Add Support for .NET Hot Reload

samples/CommunityToolkit.Maui.Markup.Sample/HotReloadHandler.cs

@@ -0,0 +1,61 @@
+using System.Diagnostics.CodeAnalysis;
+
+namespace CommunityToolkit.Maui.Markup.Sample;
+
+class HotReloadHandler : ICommunityToolkitHotReloadHandler
+{
+	public async void OnHotReload(IReadOnlyList<Type> types)
+	{
+		if (Application.Current?.MainPage is not Page mainPage)
+		{
+			return;
+		}
+
+		foreach (var type in types)
+		{
+			if (type.IsSubclassOf(typeof(Page)))
+			{
+				if (mainPage is AppShell shell)
+				{
+					var visiblePage = shell.CurrentPage;
+
+					await mainPage.Dispatcher.DispatchAsync(async () =>
+					{
+						await Shell.Current.GoToAsync(type.Name, false);
+						Shell.Current.Navigation.RemovePage(visiblePage);
+					});
+
+					break;
+				}
+				else
+				{
+					if (TryGetModalStackPage(out var modalPage))
+					{
+						await mainPage.Dispatcher.DispatchAsync(async () =>
+						{
+							await mainPage.Navigation.PopModalAsync(false);
+							await mainPage.Navigation.PushModalAsync(modalPage, false);
+						});
+					}
+					else
+					{
+						await mainPage.Dispatcher.DispatchAsync(async () =>
+						{
+							await mainPage.Navigation.PopAsync(false);
+							await mainPage.Navigation.PushAsync(modalPage, false);
+						});
+					}
+
+					break;
+				}
+			}
+		}
+	}
+
+
+	static bool TryGetModalStackPage([NotNullWhen(true)] out Page? page)
+	{
+		page = Application.Current?.MainPage?.Navigation.ModalStack.LastOrDefault();
+		return page is not null;
+	}
+}

samples/CommunityToolkit.Maui.Markup.Sample/MauiProgram.cs

@@ -33,6 +33,9 @@ public static MauiApp CreateMauiApp()
 		builder.Services.AddTransient<SettingsPage, SettingsViewModel>();
 		builder.Services.AddTransient<NewsDetailPage, NewsDetailViewModel>();
 
+		// C# Hot Reload Handler
+		builder.Services.AddSingleton<ICommunityToolkitHotReloadHandler, HotReloadHandler>();
+
 		return builder.Build();
 
 		static TimeSpan sleepDurationProvider(int attemptNumber) => TimeSpan.FromSeconds(Math.Pow(2, attemptNumber));

src/CommunityToolkit.Maui.Markup/AppBuilderExtensions.cs

@@ -5,13 +5,35 @@
 /// </summary>
 public static class AppBuilderExtensions
 {
+	static IServiceProvider serviceProvider =>
+#if WINDOWS
+		MauiWinUIApplication.Current.Services;
+#elif ANDROID
+		MauiApplication.Current.Services;
+#elif IOS || MACCATALYST
+		MauiUIApplicationDelegate.Current.Services;
+#elif TIZEN
+		throw new NotImplementedException();
+#else
+		throw new InvalidOperationException($"{nameof(IServiceProvider)} requires a platform specific implementation");
+#endif
+
 	/// <summary>
 	/// Initializes the .NET MAUI Community Toolkit Markup Library
 	/// </summary>
 	/// <param name="builder"><see cref="MauiAppBuilder"/> generated by <see cref="MauiApp"/> </param>
 	/// <returns><see cref="MauiAppBuilder"/> initialized for <see cref="CommunityToolkit.Maui.Markup"/></returns>
 	public static MauiAppBuilder UseMauiCommunityToolkitMarkup(this MauiAppBuilder builder)
 	{
+#if DEBUG
+		CommunityToolkitMetadataUpdateHandler.ReloadApplication += ReloadApplication;
+#endif
 		return builder;
 	}
+
+	static void ReloadApplication(object? sender, IReadOnlyList<Type> e)
+	{
+		var hotReloadHandler = serviceProvider.GetService<ICommunityToolkitHotReloadHandler>();
+		hotReloadHandler?.OnHotReload(e);
+	}
 }

src/CommunityToolkit.Maui.Markup/CommunityToolkit.Maui.Markup.csproj

@@ -1,8 +1,11 @@
 <?xml version="1.0" encoding="utf-8"?>
 <Project Sdk="Microsoft.NET.Sdk">
 	<PropertyGroup>
-		<TargetFramework>net7.0</TargetFramework>
+		<TargetFrameworks>net7.0;net7.0-android;net7.0-ios;net7.0-maccatalyst</TargetFrameworks>
+		<TargetFrameworks Condition="$([MSBuild]::IsOSPlatform('windows'))">$(TargetFrameworks);net7.0-windows10.0.19041.0</TargetFrameworks>
+		<TargetFrameworks Condition="'$(IncludeTizenTargetFrameworks)' == 'true'">$(TargetFrameworks);net7.0-tizen</TargetFrameworks>
 		<UseMaui>true</UseMaui>
+		<SingleProject>true</SingleProject>
 		<ImplicitUsings>enable</ImplicitUsings>
 		<GenerateDocumentationFile>true</GenerateDocumentationFile>
 	</PropertyGroup>

src/CommunityToolkit.Maui.Markup/CommunityToolkitMetadataUpdateHandler.cs

@@ -0,0 +1,34 @@
+#if DEBUG
+[assembly: System.Reflection.Metadata.MetadataUpdateHandler(typeof(CommunityToolkit.Maui.Markup.CommunityToolkitMetadataUpdateHandler))]
+namespace CommunityToolkit.Maui.Markup;
+
+static class CommunityToolkitMetadataUpdateHandler
+{
+	static readonly WeakEventManager reloadApplicationEventHandler = new();
+
+	public static event EventHandler<IReadOnlyList<Type>> ReloadApplication
+	{
+		add => reloadApplicationEventHandler.AddEventHandler(value);
+		remove => reloadApplicationEventHandler.RemoveEventHandler(value);
+	}
+
+	static void UpdateApplication(Type[]? types)
+	{
+#pragma warning disable CS8625 // Cannot convert null literal to non-nullable reference type.
+		reloadApplicationEventHandler.HandleEvent(null, types?.ToList() ?? Enumerable.Empty<Type>(), nameof(ReloadApplication));
+#pragma warning restore CS8625 // Cannot convert null literal to non-nullable reference type.
+	}
+}
+#endif
+
+/// <summary>
+/// Interface for handling C# Hot Reload requests
+/// </summary>
+public interface ICommunityToolkitHotReloadHandler
+{
+	/// <summary>
+	/// Executes when C# Hot Reload is invoked
+	/// </summary>
+	/// <param name="types">A <see cref="IReadOnlyList{Type}"/> contianing the types that have been changed in code.</param>
+	void OnHotReload(IReadOnlyList<Type> types);
+}