Apple just announced a new language called Swift. I took a look at the language manual, here is a quick overview:

  • Statically typed with type inference.
  • Generics.
  • Closures.
  • No exceptions.
  • Extension methods.
  • Properties (syntax similar to C#), including lazy properties with the "@lazy" annotation.
  • Functions, methods and type (static) methods.
  • Support for observers (with "willSet" and "didSet"). Interesting to see the observer pattern baked in a language although I’m more partial to event buses for this kind of thing.
  • Enums.
  • Classes and structures (structures have restrictions regarding inheritance and other things).
  • For and while loops (statements, not expressions).
  • "mutating" keyword.
  • Named parameters.
  • Deinitializers (finalizers).
  • Protocols (interfaces).
  • Optional chaining with "a?.b?.c" and forced dereference with "!."“.
  • Convenient “assign and test”: "if let person = findPerson() ...".
  • Type casting with "is", down casting with "as?" (combines nicely with the "let" syntax. Ceylon does it right too).

Very interesting overall, and a clear step up from Objective C. From the feature set, I would say the language that Swift has the most overlap with is Kotlin, which is great news for Apple developers.

Update: discussion on reddit.