These projections contains a subset of APIs for the Windows App SDK, minus those of WinUI (Microsoft.UI.Xaml). See official documentation for more information on these components:

SDK Versions

Windows SDK: 10.0.18362.0
Windows App SDK: 1.5-preview1

Project Configuration

The bindings are generated from WinMD files, found in NuGet packages on Nuget.org. There are two key files which drive this:

projections.json - this specifies the project/package and which apis to include in the projection
generate-bindings.ps1 - this file reads projections.json and generates the appropriate bindings.

Known Issues and Limitations

Only x64 architecture is supported right now
The developer experience for consuming WinRT APIs from Swift is a work in progress. Due to current limitations, not all APIs can be generated as this causes export limit issues.
The APIs listed in projections.json are required for the other swift-* projects to build. Modify a projections.json in any one of those projects could require an update here.

Using Windows App SDK

In order to use the Windows App SDK, you need to download the Windows App SDK from here: https://aka.ms/windowsappsdk/1.5/1.5.240205001-preview1/windowsappruntimeinstall-x64.exe