Earlier quoted context omitted.
Right, but you can’t have a single package containing both ObjC and Swift. It’s a limitation of SwiftPM that has prevented me from using it for a few projects (I am using it in several others, though).
You can mix them, it just has to be released as a binary framework which is a bit annoying as I would prefer a pure source release but it does work.
My involvement with MacOS development is somewhat limited and I have no plans publishing any packages yet ;)