> ... iirc this was because Swift was evolving so fast that Apple wasn't willing or able to commit to including a bunch with iOS. Not just that - they wanted t

> ... iirc this was because Swift was evolving so fast that Apple wasn't willing or able to commit to including a bunch with iOS. Not just that - they wanted to have language features for stability and migration which they hadn't fully flushed out yet and implemented. Now, Swift is part of the OS itself - which has good and bad sides, because policies to support older versions of iOS also mean you can't fully leverage all the new language features.