Missing and outdated documentation. For an iOS/macOS app at the moment I'm looking into how to modify an AVFoundation video copy (multiple splits and deletions of segments) with Swift. The framework grew up with Objective-C, and one of the docs outright shows Objective-C code while Swift is selected: https://developer.apple.com/documentation/avfoundation/avmut.... Conceptual guidance is hard to find, and the Apple documentation archive's link for "AVFoundation Programming Guide" is broken.