Apple Silicon support (it builds local too) - #25

This local build work on my side

I don't know much about xcode or these builds, but the link you posted me to UTM was very help to getting CI set up for gitx. FWIW, they appear to be building for arm64, and it looks like they're doing it via the build matrix and explicitly passing -arch ${{ matrix.arch }} to xcodebuild. Something like this:

      matrix:
        arch: [ x86_64 ]
        xcode: [ Xcode_12.5, Xcode_13.1, Xcode_13.2.1, Xcode_13.0, Xcode_12.4 ]
        include:
          - arch: arm64
            xcode: Xcode_13.2.1
...
      - name: Build project
        run: xcodebuild -workspace ObjectiveGitFramework.xcworkspace -scheme "ObjectiveGit Mac" -arch ${{ matrix.arch }} archive

I'm sure they're more to it, but perhaps this might be helpful?

Actually, they're doing 2 builds:

• the matrix arch build at https://github.com/utmapp/UTM/blob/master/.github/workflows/build.yml#L73
• a universal build at https://github.com/utmapp/UTM/blob/master/.github/workflows/build.yml#L117

Both of those call into https://github.com/utmapp/UTM/blob/master/scripts/build_utm.sh, which looks like it ends up calling xcodebuild with -arch x86_64 -arch arm64 for the universal build. (ie it passes both -arch flags)

Again, I'm in over my head on this, and I don't even use an M1, but perhaps this will be helpful to you.

I moved to similar approach like with libgit2.a and it build locally with M1 as well.
If we find a better solution, we can change this anytime