Migrating from Preview 7 to 8

This document covers the main differences between previews that you'll need to adopt as you are updating projects from release to release.

Pre-Steps

• Uninstall all versions of .NET 6 previews via Add/Remove Programs
• Uninstall all versions of Visual Studio 2022

Minimum Requirements

• Visual Studio 2022 Preview 4 with .NET MAUI workload requirements (see installation docs)
• Android API 31 obtained via Android Studio
• OpenJDK 11
• Xcode 13 latest beta (Mac build host)
• Single Project extension for Windows App SDK

1 - Startup.cs to MauiProgram.cs

.NET MAUI now aligns with ASP.NET and Blazor with our usage of this host builder pattern.

1. Rename Startup.cs to MauiProgram.cs
2. Update the class and method to match the template

using Microsoft.Maui;
using Microsoft.Maui.Hosting;
using Microsoft.Maui.Controls.Compatibility;
using Microsoft.Maui.Controls.Hosting;

namespace MauiApp._1
{
	public static class MauiProgram
	{
		public static MauiApp CreateMauiApp()
		{
			var builder = MauiApp.CreateBuilder();
			builder
				.UseMauiApp<App>()
				.ConfigureFonts(fonts =>
				{
					fonts.AddFont("OpenSans-Regular.ttf", "OpenSansRegular");
				});

			return builder.Build();
		}
	}
}

3. Update Platforms/Android/MainApplication.cs to implement CreateMauiApp() and update the class inheritance. Do the same for Platforms/iOS/AppDelegate.cs, and Platforms/MacCatalyst/AppDelegate.cs.

using System;
using Android.App;
using Android.Runtime;
using Microsoft.Maui;

namespace MauiApp._1
{
	[Application]
	public class MainApplication : MauiApplication
	{
		public MainApplication(IntPtr handle, JniHandleOwnership ownership)
			: base(handle, ownership)
		{
		}

		protected override MauiApp CreateMauiApp() => MauiProgram.CreateMauiApp();
	}
}

2 - Windows Platform Single Project

The Windows platform is now part of the .NET MAUI single project.

1. Use the template to add the base files to Platforms/Windows and update for your namespace.
2. Copy into Platforms/Windows and platform specific code you have in your Windows project.
3. Add any NuGet dependencies specific to Windows to the Single Project.
4. Add launchSettings.json to the Properties folder.
5. Remove your Windows project from the solution.
6. Update your csproj file with the Windows TargetFramework and platform dependencies.

<Project Sdk="Microsoft.NET.Sdk">

	<PropertyGroup>
		<TargetFrameworks>net6.0-ios;net6.0-android;net6.0-maccatalyst</TargetFrameworks>
		<!-- <TargetFrameworks Condition="$([MSBuild]::IsOSPlatform('windows')) and '$(MSBuildRuntimeType)' == 'Full'">$(TargetFrameworks);net6.0-windows10.0.19041</TargetFrameworks> -->
		<OutputType>Exe</OutputType>
		<RootNamespace>MauiApp._1</RootNamespace>
		<UseMaui>true</UseMaui>
		<SingleProject>true</SingleProject>
		<EnablePreviewMsixTooling>true</EnablePreviewMsixTooling>

		<!-- Display name -->
		<ApplicationTitle>MauiApp.1</ApplicationTitle>

		<!-- App Identifier -->
		<ApplicationId>com.companyname.MauiApp._1</ApplicationId>

		<!-- Versions -->
		<ApplicationVersion>1.0</ApplicationVersion>
		<AndroidVersionCode>1</AndroidVersionCode>

		<!-- Required for C# Hot Reload -->
		<UseInterpreter Condition="'$(Configuration)' == 'Debug'">True</UseInterpreter>
	</PropertyGroup>

	<ItemGroup>
		<!-- App Icon -->
		<MauiImage
			Include="Resources\appicon.svg"
			ForegroundFile="Resources\appiconfg.svg"
			IsAppIcon="true"
			Color="#512BD4" />

		<!-- Splash Screen -->
		<MauiSplashScreen Include="Resources\appiconfg.svg" Color="#512BD4" />

		<!-- Images -->
		<MauiImage Include="Resources\Images\*" />

		<!-- Custom Fonts -->
		<MauiFont Include="Resources\Fonts\*" />
	</ItemGroup>

	<ItemGroup Condition="$(TargetFramework.Contains('-windows'))">
		<!-- Required - WinUI does not yet have buildTransitive for everything -->
		<PackageReference Include="Microsoft.WindowsAppSDK" Version="WINDOWSAPPSDK_VERSION" />
		<PackageReference Include="Microsoft.WindowsAppSDK.Foundation" Version="WINDOWSAPPSDK_VERSION" />
		<PackageReference Include="Microsoft.WindowsAppSDK.WinUI" Version="WINDOWSAPPSDK_VERSION" />
		<PackageReference Include="Microsoft.WindowsAppSDK.InteractiveExperiences" Version="WINDOWSAPPSDK_VERSION" NoWarn="NU1701" />
	</ItemGroup>

	<PropertyGroup Condition="$(TargetFramework.Contains('-windows'))">
		<OutputType>WinExe</OutputType>
		<RuntimeIdentifier>win-x64</RuntimeIdentifier>
	</PropertyGroup>
	
	<PropertyGroup>
		<!-- Required - WinUI can't deploy in a multi-targeting environment -->
		<RuntimeIdentifier Condition="$(TargetFramework.Contains('-windows'))">win-x64</RuntimeIdentifier>
	</PropertyGroup>

</Project>

3 - Update Android Theme

Android now uses the MaterialTheme which may conflict with older themes and styles. Update your MainActivity.cs and/or styles.xml to be based on the @style/Maui.SplashTheme Theme.

using Android.App;
using Android.Content.PM;
using Microsoft.Maui;

namespace MauiApp._1
{
	[Activity(Theme = "@style/Maui.SplashTheme", MainLauncher = true, ConfigurationChanges = ConfigChanges.ScreenSize | ConfigChanges.Orientation | ConfigChanges.UiMode | ConfigChanges.ScreenLayout | ConfigChanges.SmallestScreenSize)]
	public class MainActivity : MauiAppCompatActivity
	{
	}
}