When I was working with it (I was there, 4000 years ago) there was some talk about Swift for the server, but neither obj-C nor Swift ever really breached containment of the Apple ecosystem and -tooling. Which is a shame because at the time I enjoyed working in XCode. Who knew using a mouse swipe to go back in your code would be so natural? Not any other IDE developer, ever.

Last time I worked with it it felt very sluggish and buggy though, in theory building UI elements with SwiftUI is great, in practice it was slow and needed to restart very often, and that was with simple components.