SwiftUI compatibility APIs in GNUstep's graphics stack (Was: Which ObjC2.0 features are missing in the latest GCC?)

[Ivan Vučica]

On Wed, Nov 27, 2019 at 3:32 AM Maxthon Chan <xcvista@me.com> wrote:
>
> When talking about SwiftUI, I mean having CAAppKitBridge/Opal/Back implement 
> SwiftUI API as its interface to the upper layers.

I am getting increasingly confused here. Why would these particular
libraries implement the SwiftUI APIs?

Especially CAAppKitBridge which tries to use Opal backend in
gnustep-back to paint gnustep-gui's views into CA's layers, by
creating a GL view, scheduling repaints, etc?

Was I under the wrong impression that SwiftUI is a replacement /
wrapper around AppKit/UIKit? In fact, Apple's basic tutorials suggest
that it sits around / in place of UIKit, so does this discussion even
apply in context of AppKit APIs?

What Mac-native open source apps can you point me at to basically
understand SwiftUI without reading through tutorials?