Add other backend UI framework on non-Darwin platform

[Kyle-Ye]

• Add AppKid as UIKit/AppKit alternative on Linux platform
• Take swift-cross-ui's code to use gtk4 as UIKit/AppKit alternative on Windows/Linux platform
• https://github.com/AparokshaUI/adwaita-swift
• https://github.com/frang75/nappgui_src
• https://github.com/flowkey/UIKit-cross-platform
• https://github.com/avaidyam/DIYAnimation

Will work on this when basic UIView/NSView support is ready.

[chawyehsu]

I wonder if it's possible to use the WinUI infra as the backend on Windows platform.

[Kyle-Ye]

I wonder if it's possible to use the WinUI infra as the backend on Windows platform.

Theoretically, it is possible. Recently, I have started to add some platform-related code (UIView/NSView) and rendering layer things.

If you are interested you are welcome to contribute platform code on the WinUI layer later.

[Kyle-Ye]

https://github.com/microsoft/WinObjC.git

There is a WinObjC project which provide UIKit compatible API on Windows too.

[chawyehsu]

IIUC that framework is basically obsolete, it's a pretty good reference though.

[ethanc8]

I am working on GNUstep, which provides an almost complete Foundation implementation and a very mature but incomplete AppKit implementation in Objective-C. The issue is that Swift<->ObjC bridging is broken on Linux, and it will need a lot of fixes to the Swift compiler to fix that.

[ethanc8]

GNUstep supports almost every platform -- X11 and Wayland on Linux, BSD, and probably any other Unix that's supported by LLVM, and also supports Windows.

[Kyle-Ye]

I am working on GNUstep, which provides an almost complete Foundation implementation and a very mature but incomplete AppKit implementation in Objective-C. The issue is that Swift<->ObjC bridging is broken on Linux, and it will need a lot of fixes to the Swift compiler to fix that.

Glad if you'd like to help replace the default CoreFoundation/Foundation/AppKit dependency with the your open source implementation.

[CmST0us]

Is it possible to use LVGL as backend ?
https://github.com/lvgl/lvgl

[ethanc8]

If we use GNUstep's AppKit as a backend, will it be necessary for it to support CoreAnimation-AppKit bridging? How important is CoreAnimation to SwiftUI users? Unfortunately the CoreAnimation-AppKit bridging in GNUstep is not working well, and I am unable to fix it without help from other contributors who are currently very busy.