NSCopyObject isn't something that was "dropped into Swift," it's a function that has existed since the mid 90s, and is available in Swift because Swift can call

NSCopyObject isn't something that was "dropped into Swift," it's a function that has existed since the mid 90s, and is available in Swift because Swift can call C and Objective-C functions. But yes, you do have to live with the history of the platform you're developing for. Opportunities to break backwards-compatibility are few and far-between, because users don't like when OS updates make their apps stop working.