Why there is not available SDK for macOS 12 with Concurrency features?

Hello, I try to compile simple package for beta macOS Monterey. I have last version of Xcode Version 13.0 (13A233), my Package file includes

// swift-tools-version:5.5
    platforms: [

My target for the package is MyMac and I get the next compiler warning
../Package.swift The macOS deployment target 'MACOSX_DEPLOYMENT_TARGET' is set to 12.0, but the range of supported deployment target versions is 10.9 to 11.3.99.

And when I try to use @MainActor above the class, I also get the error

@MainActor // Unknown attribute 'MainActor'

class Pool {


While when I switch the target to iPhone with iOS 15 it become visible. Where I can get the available SDK for macOS 12? Because I instaled the beta just to touch the Concerrency without having to run the simulator

1 Like

macOS 12 SDK is available in Xcode 13 betas but not the released Xcode 13. It’ll be provided with release versions of Xcode when macOS 12 is released.


macOS 12 is still in beta and non-beta versions of Xcode don't include SDKs for beta OSes. Last year there was a 12.2 beta released at the same time as Xcode 12 which included the macOS 11 beta SDK but for whatever reason there was nothing similar this year and you have to continue to use Xcode 13 beta 5.

1 Like

I didn't make in time to download Xcode beta, and it looks like all beta versions of Xcode became unavailable after the release of 13.0

Older versions of Xcode, including the Xcode 13 betas, are available from the More Downloads page.