How to upgrade from Xamarin to .NET 7

There are two ways to migrate an application to .NET 7.

The forward looking path using the WinUI/WinApp SDK APIs

1. In a separate folder, create a new application from the templates using dotnet new unoapp -o MyApp (MyApp being of the same name as your existing app), or by using the Visual Studio Uno Platform App template
2. Move the MyApp.Mobile project folder and include it in your existing solution
3. Make the adjustments to move from the UWP APIs to the WinUI APIs
4. Optionally convert your legacy Xamarin heads to use Uno.WinUI instead of Uno.UI

Additional considerations

Since .NET 7 breaks binary compatibility with Xamarin, most of the existing nuget packages that target monoandroidXX, xamarinios10 and xamarinmac20 (bindings to native SDKs are a good example) will not work properly and will need an updated version that are compatible with net7.0-ios, net7.0-android, and net7.0-maccatalyst.

Xamarin Support Policy

As defined by Microsoft support policy for Xamarin (as of 2022-08-25):

Xamarin support will end on May 1, 2024 for all Xamarin SDKs. Android 13 and Xcode 14 SDKs (iOS and iPadOS 16, macOS 13) will be the final versions Xamarin will target.

Uno Platform is going provides support for Xamarin (monoandroid12, monoandroid13, xamarinios10 and xamarinmac20) by that date as well in the Uno 4.x releases. Uno 5.0 and later does not support Xamarin anymore. Note that later on, apps built with these SDK will not be accepted by both Apple and Google stores.