In my view, as a MacOS programmer, I still prefer to ask elsewhere for help with purely Apple frameworks, tools (Xcode, IB, etc.), and not load down the discussions in these forums on purely Apple issues. It's not even clear if the relevant folks from Apple staff outside the Swift sphere of influence read this forum enough to be drawn into the discussions.
If we are not careful, we will get users who essentially ask, for example, "I want to build an iOS app that does x,y,z. How do I do it?" It's happening over in the Apple Dev forums, and I'm seeing several incursions here of this type. If a question is about a Swift technology (propertyWrappers, for example) that are used in Apple frameworks, but, are, or could be generally useful to most everyone in the community, then it's appropriate here, even if the context of the problem is in an iOS or macOS context. In my mind, until SwiftUI and Combine are released by Apple to open-source, they should be treated as Apple frameworks. But, this is a gray area since senior members of the development team seem to be more tolerant of these questions herein, probably because these two frameworks are really testbeds for future Swift evolution of the Swift open-source system, even if SwiftUI and Combine remain Apple proprietary.