Swift Gives You Extensive Control Over Memory Management and Copying

In Objective C, you have a very kind of limited selection of data structures. Swift goes this protocol oriented route of defining these things in terms of protocols. And the benefit of this isn't immediately obvious, but it becomes clear later on when you have all kinds of performance optimizations that are built into Swift. It can kind of vent like a lazy array or a lazy collection of something and still behaves exactly the same as if it was a plain array.