Conditionally revealing symbols from a module only when SwiftUI is imported

[xwu (Xiaodi Wu)]

@dorindanciu

From what I've found so far, it looks like for every framework where some SwiftUI additions are provided, there is another framework titled _FrameworkName_SwiftUI (i.e. _SwiftData_SwiftUI, _MapKit_SwiftUI, _AVKit_SwiftUI). These frameworks are importing the base framework, and defining correspondent SwiftUI types to be used in conjunction with the types found in the base framework.

This is a private/prototype feature called cross-import overlays; it's not been formalized for public use.