Platform.Maui.MacOS.BlazorWebView 0.3.0

.NET MAUI Backends for Apple TV & macOS (AppKit)

Custom .NET MAUI backends targeting platforms not officially supported by MAUI — Apple TV (tvOS via UIKit) and macOS (native AppKit, not Mac Catalyst).

Both backends use the platform-agnostic MAUI NuGet packages (net10.0 fallback assemblies) and provide custom handler implementations that bridge MAUI's layout/rendering system to the native platform UI frameworks.

Inspiration: The Xamarin.Forms project previously had a macOS AppKit backend (Xamarin.Forms.Platform.MacOS). While this project uses MAUI's handler architecture rather than the legacy renderer approach, some of that codebase is useful as a reference for mapping AppKit native controls.

https://github.com/user-attachments/assets/035de5fa-bda6-49d1-98f6-41cd4d6ff559

Quick Start — Setting Up a macOS MAUI App

1. Create the project

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>net10.0-macos</TargetFramework>
    <OutputType>Exe</OutputType>
    <UseMaui>true</UseMaui>
    <SingleProject>true</SingleProject>
    <SupportedOSPlatformVersion>14.0</SupportedOSPlatformVersion>
    <ApplicationTitle>My macOS App</ApplicationTitle>
    <ApplicationId>com.example.myapp</ApplicationId>
  </PropertyGroup>

  <ItemGroup>
    <PackageReference Include="Microsoft.Maui.Controls" Version="$(MauiVersion)" />
    <PackageReference Include="Platform.Maui.MacOS" Version="*" />
    <PackageReference Include="Platform.Maui.Essentials.MacOS" Version="*" />
  </ItemGroup>

  
  <ItemGroup>
    <MauiIcon Include="Resources\AppIcon\appicon.png" />
  </ItemGroup>
</Project>

2. Entry point (Main.cs)

using AppKit;

public class MainClass
{
    static void Main(string[] args)
    {
        NSApplication.Init();
        NSApplication.SharedApplication.Delegate = new MauiMacOSApp();
        NSApplication.Main(args);
    }
}

3. App delegate (MauiMacOSApp.cs)

using Foundation;
using Microsoft.Maui.Platform.MacOS;

[Register("MauiMacOSApp")]
public class MauiMacOSApp : MacOSMauiApplication
{
    protected override MauiApp CreateMauiApp() => MauiProgram.CreateMauiApp();
}

4. MAUI program (MauiProgram.cs)

using Microsoft.Maui.Platform.MacOS.Hosting;

public static class MauiProgram
{
    public static MauiApp CreateMauiApp()
    {
        var builder = MauiApp.CreateBuilder();
        builder
            .UseMauiAppMacOS<App>()
            .AddMacOSEssentials()
            .ConfigureFonts(fonts =>
            {
                fonts.AddFont("OpenSans-Regular.ttf", "OpenSansRegular");
            });

        return builder.Build();
    }
}

5. App class (App.cs)

public class App : Application
{
    protected override Window CreateWindow(IActivationState? activationState)
        => new Window(new MainPage());
}

App Icons

The Platform.Maui.MacOS NuGet package includes MSBuild targets that automatically process MauiIcon items — the same item type used by MAUI's Resizetizer for iOS, Android, and Windows.

<ItemGroup>
    <MauiIcon Include="Resources\AppIcon\appicon.png" />
</ItemGroup>

At build time, the targets:

1. Use sips to resize the source image (SVG or PNG) to all 10 required macOS icon sizes (16×16 through 512×512@2x)
2. Use iconutil to create the .icns file
3. Inject CFBundleIconFile into the app manifest via PartialAppManifest
4. Add the .icns as a BundleResource

No manual .icns creation or Info.plist editing required.

macOS Platform-Specific APIs

Shell — Native Sidebar

The macOS backend supports Shell with a native macOS sidebar using NSOutlineView source list, providing a Finder/System Settings-like navigation experience. Configure it with attached properties on your Shell:

using Microsoft.Maui.Platform.MacOS;

public class AppShell : Shell
{
    public AppShell()
    {
        FlyoutBehavior = FlyoutBehavior.Locked;

        // Enable native NSOutlineView sidebar
        MacOSShell.SetUseNativeSidebar(this, true);

        // Allow user to resize sidebar by dragging the divider (default: true)
        MacOSShell.SetIsSidebarResizable(this, true);

        var generalSection = new FlyoutItem { Title = "General" };

        var home = new ShellContent { Title = "Home", ContentTemplate = new DataTemplate(typeof(HomePage)) };
        MacOSShell.SetSystemImage(home, "house.fill");  // SF Symbol icon
        generalSection.Items.Add(home);

        var settings = new ShellContent { Title = "Settings", ContentTemplate = new DataTemplate(typeof(SettingsPage)) };
        MacOSShell.SetSystemImage(settings, "gear");
        generalSection.Items.Add(settings);

        Items.Add(generalSection);
    }
}

MacOSShell Attached Properties

FlyoutPage — Native Sidebar

For FlyoutPage, you can also use a native sidebar with structured items:

using Microsoft.Maui.Platform.MacOS;

var flyoutPage = new FlyoutPage();

MacOSFlyoutPage.SetSidebarItems(flyoutPage, new List<MacOSSidebarItem>
{
    new MacOSSidebarItem
    {
        Title = "Library",
        Children = new List<MacOSSidebarItem>
        {
            new MacOSSidebarItem { Title = "Music", SystemImage = "music.note" },
            new MacOSSidebarItem { Title = "Photos", SystemImage = "photo" },
        }
    }
});

MacOSFlyoutPage.SetSidebarSelectionChanged(flyoutPage, item =>
{
    // Handle selection
});

To use the native sidebar handler, register it in MauiProgram.cs:

builder.ConfigureMauiHandlers(handlers =>
{
    handlers.AddHandler<FlyoutPage, NativeSidebarFlyoutPageHandler>();
});

MacOSFlyoutPage Attached Properties

MacOSSidebarItem Properties

Project Structure

src/
  Platform.Maui.MacOS/              # macOS AppKit backend library (net10.0-macos)
  Platform.Maui.MacOS.BlazorWebView/ # Blazor Hybrid support for macOS
  Platform.Maui.TvOS/               # tvOS backend library (net10.0-tvos)
  Platform.Maui.Essentials.MacOS/   # macOS Essentials library
  Platform.Maui.Essentials.TvOS/    # tvOS Essentials library
samples/
  Sample/                           # Shared sample code (Pages, Platforms/)
  SampleTv/                         # tvOS sample app
  SampleMac/                        # macOS sample app

Note: There is also a Sample/Sample.csproj that multitargets both net10.0-tvos and net10.0-macos, but it is not yet working. Use SampleTv and SampleMac to build and run the individual platform samples.

Handlers Implemented

Controls

Pages & Navigation

Collections

Layouts

All layouts work on both platforms: VerticalStackLayout, HorizontalStackLayout, Grid, FlexLayout, AbsoluteLayout, ScrollView, ContentView, Border, Frame.

Graphics & Shapes

Gestures

Infrastructure

BlazorWebView (macOS only)

The BlazorWebView implementation uses a custom MacOSBlazorWebView control — the built-in MAUI BlazorWebView internally casts to the iOS/Catalyst handler, which fails on AppKit.

Setup

// In MauiProgram.cs
builder.AddMacOSBlazorWebView();

Usage

using Microsoft.Maui.Platform.MacOS.Controls;

var blazorView = new MacOSBlazorWebView
{
    HostPage = "wwwroot/index.html",
    HeightRequest = 400
};
blazorView.RootComponents.Add(new BlazorRootComponent
{
    Selector = "#app",
    ComponentType = typeof(MyApp.Components.Counter)
});

Static web assets (wwwroot/) must be included as BundleResource items in the project file:

<ItemGroup>
    <BundleResource Include="wwwroot\**" />
</ItemGroup>

Lifecycle Events

Both platforms fire standard IWindow lifecycle methods and support MAUI's ConfigureLifecycleEvents builder pattern.

IWindow Lifecycle

Platform-Specific Lifecycle Events

builder.ConfigureLifecycleEvents(events =>
{
    events.AddMacOS(macOS => macOS
        .DidFinishLaunching(notification => { /* NSNotification */ })
        .DidBecomeActive(notification => { })
        .DidResignActive(notification => { })
        .DidHide(notification => { })
        .DidUnhide(notification => { })
        .WillTerminate(notification => { })
    );
});

Essentials

Platform-specific implementations of MAUI Essentials APIs.

Setup

// In MauiProgram.cs
builder.AddMacOSEssentials();

Then use the standard MAUI Essentials APIs:

var appName = AppInfo.Name;
var version = AppInfo.VersionString;
var theme = AppInfo.RequestedTheme;
var model = DeviceInfo.Model;

Supported APIs

Prerequisites

Important: JetBrains Rider and Visual Studio will not compile these projects. The net10.0-tvos and net10.0-macos TFMs are not recognized by IDE build systems. All building and running must be done through the CLI using the dotnet command.

.NET 10 SDK

Install the latest .NET 10 preview SDK from dotnet.microsoft.com.

Workloads

dotnet workload install tvos
dotnet workload install macos
dotnet workload list   # verify

Xcode

Xcode must be installed for Apple platform SDKs:

sudo xcode-select -s /Applications/Xcode.app

Building & Running

# Build
dotnet build samples/SampleMac/SampleMac.csproj
dotnet build samples/SampleTv/SampleTv.csproj

# Run macOS
dotnet build samples/SampleMac/SampleMac.csproj -t:Run

# Run tvOS (simulator)
dotnet build samples/SampleTv/SampleTv.csproj -t:Run

Note: Do not use dotnet build "MAUI Platforms.slnx" — build projects individually.

Key Technical Notes

• MAUI NuGet packages resolve to the net10.0 (platform-agnostic) assembly for unsupported TFMs. ToPlatform() returns object — custom ViewExtensions casts to the native view type.
• The platform-agnostic ViewHandler has no-op PlatformArrange and returns Size.Zero. Custom base handlers (MacOSViewHandler/TvOSViewHandler) override these to bridge MAUI layout to native view frames.
• macOS NSView uses bottom-left origin by default. All container views override IsFlipped => true for MAUI's top-left coordinate system.
• macOS NSView has no SizeThatFits() — the base handler uses IntrinsicContentSize and FittingSize, with a custom SizeThatFits method on MacOSContainerView.
• Sample apps use pure C# pages (no XAML) to avoid XAML compilation issues on unsupported platforms.
• The macOS window uses FullSizeContentView style with TitlebarAppearsTransparent = true so the Shell sidebar extends under the titlebar with proper macOS vibrancy.

Dialogs

Dialogs (DisplayAlertAsync, DisplayPromptAsync) are supported on macOS via NSAlert, but are not yet supported on tvOS.

MAUI's dialog system uses an internal AlertManager with IAlertManagerSubscription. On macOS, we implement this via DispatchProxy reflection. tvOS uses AOT compilation which doesn't support DispatchProxy. Until IAlertManagerSubscription is made public in MAUI (see the proposal), tvOS dialog support is blocked.

TODO

General

• Multitarget Sample project
• XAML Compilation
• Multi-window support
• Accessibility support

tvOS Specific

• Focus Engine integration
• Top Shelf extensions
• TV remote menu button handling

macOS Specific

• Touch Bar support
• Drag and drop
• Multiple windows

Broader Goals

• NuGet packaging
• CI/CD pipeline