SwiftUI isn’t UIKit-specific. Display Postscript hasn’t existed since the OS was called NeXT, 20+ years ago, and was never on any iDevice. Cocoa is an alias for AppKit + CoreData, and iOS uses CocoaTouch instead.
You’re right, yet this doesn’t directly address what parent said, in fact it’s somewhat agreeing with the point, that there’s a ton of influence left behind by these things, even though they are not there anymore.