If you are good with C++, you can do your development in Tier 2 on a Mac with no problem.
However, you would not be able to broadcast to a Player from Xcode. If it is important for your testing to do broadcasting, that might be an issue.
But, you can run your app directly from Xcode.
Of course, this can't happen until TGC gets the libraries and projects done for Mac (and iOS and Android) for AppGameKit V2.
AGK V1 works just fine in the Xcode projects. And Tier 2 is very usable there.
Cheers,
Ancient Lady
AGK Community Tester and AppGameKit Master