You won't be able to edit a XIB without fixing AL issues in 1-2 years, and the XIB will be unreadable in 5-10.
The part of Xcode that used to be Interface Builder is still useful for prototyping, but don't ship that!
Write complex UI in code. Autolayout strings in code aren't as bad as the obscure UI, but one can just as easily compute and set frames.
Choose any language except Swift.
Or, good luck with your walking-dead software.