It's Apple's future for cross platform (ios/macos/watch) applications. Hardcore longtime mac devs find it frustratingly unable to do some complex things they want to do (and yay that they do!) to take advantage of the mac OS. But you don't want that; you just want to interact with your own code. And SwiftUI will let you do the basic stuff easily...and likely just (well, almost just) recompile your program for your iphone or ipad.