There's no argument about Swift. It's a no-brainer decision to go with Swift at this point. SwiftUI however is a different story. You still hit walls hard with SwiftUI, regularly coming up against things that are either impossible or require ridiculous hacks or workarounds. But I am hopeful that SwiftUI will continue to improve. It has great potential. Apple's statement here is direction-setting – that's the path where they want to direct future development.