@Slava_Pestov My use case is different (posted here - and that's where I got referred to this thread).
I want to break up my SceneDelegate into different targets. Problem is, those methods in the other target are not seen as part of the SceneDelegate class. Thanks to this thread, I understand the problem with Swift extensions, but ObjC categories should work? I attempted the same using ObjC category i.e., I created the SceneDelegate in the ObjC layer in a static library and extended it another library. The delegate methods defined in another library are not invoked by iOS.