Can I simulate traits/mixins in Swift?

Question

Does Swift have a way of mixing in traits, a la Scala? The section of the Swift book on using extensions to add protocols to existing classes comes tantalizingly close. However,

Answer 1

As of Swift 2.0, yes!

Providing Default Implementations

You can use protocol extensions to provide a default implementation to any method or property requirement of that protocol. If a conforming type provides its own implementation of a required method or property, that implementation will be used instead of the one provided by the extension.