I've built my own compatibility layer once that could hide the differences across Cocoa and UIKit. It was easier than I thought actually, though I made it only

I've built my own compatibility layer once that could hide the differences across Cocoa and UIKit. It was easier than I thought actually, though I made it only for the things that I needed and not more than that. It came down to mapping UIKit symbols on the Mac and also implementing the missing methods. You build and debug the app on iOS and then it compiles and runs on the Mac, that's all.