Sure, the lineage of declarative UI is pretty long. I'm aware of Windows resource files and the Mac's resource files that inspired them; there may be earlier antecedents on 8-bit micros.
SwiftUI provides a fundamentally different way of thinking about UI composition and managing data flow in your app. Much of the GUI logic simply disappears. Syntactically and functionally, it seems like something structured like it would be a great fit for a cross-platform Lisp UI framework.
I mean, for instance, oh, Windows resource files.
Glancing through CLIM, I also don't see anything like that sort of separation between GUI logic and form.