i am posting this because i seek an understanding of Apple's cross-platform UI strategy.
That's pretty easy. Deprecate all platforms other than iOS. Then re-brand iOS to match product lines.
my background is UIKit, Core Animation, and Chameleon a UIKit workalike for (then) OSX.
Chameleon? The Github project hasn't been updated in 11 years. The project web site redirects to what appears to be a Vietnamese sports gambling site.
UIKit evolved and Mac Catalyst came along. what is the positioning of Mac Catalyst? it extends and at the same time it limits AppKit. is it an AppKit extension or is it a UI framework of its own? a Mac Catalyst app is not an AppKit app, or is it? or is it sort-of?
I don't know if Apple even thinks in terms of those kinds of architectures and strategies. Or if they do, they sure don't make it public. And even if they did, it wouldn't necessarily mean anything to 3rd party developers. It's a radically different perspective than anything Apple enjoys internally.
SwiftUI sit on top of UIKit (for iOS) and Mac Catalyst (for macOS) or is it an unrelated technology?
I can't speak to Official Apple Positions. I can tell you that those Official Positions can and do change regularly and without notice. As a 3rd party developer, it's closer to reading tea leaves than to reading documentation.
From my completely non-official, outsider perspective, Mac Catalyst is dead. SwiftUI is (for now) the official API of the Future for both iOS and macOS. Unfortunately, Swift (and SwiftUI) are still under active development. Bugs and other limitations are common. I don't know if this is something that will be fixed or if it is a strategy to more permanently limit 3rd party app complexity, customization, and support for old OS versions.
more recently i see CoreUI messages in the debugger console. where does that fit in? will future UIKit, AppKit, Mac Catalyst, and SwiftUI all build upon CoreUI? will CoreUI become a public framework like CoreGraphics, CoreAnimation?
There is no one outside Apple who can answer that question, and no one inside Apple who will. The Apple rumour sites are predicting a major redesign this year. That's seems reasonable.
in the old Apple docs there were block diagram overviews of how the individual frameworks would sit one on top of the other. this is what i am looking for...
I'm sure if any such documentation is produced for public consumption, it will be made available in exactly 3 months from now.
