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

One way to simulate mixing is use generic function to provide implementation

For example with these protocols

protocol Named {
    func GetName() -> String
}

protocol NamedExtension {
    func GetLowercaseName() -> String
    func GetUppercaseName() -> String
}

I want some class to implement GetName() and use mixing so they also get GetLowercaseName() and GetUppercaseName() without implement them

This is the implementation of NamedExtension as in free function

func GetLowercaseNameImpl(obj:T) -> String {
    return obj.GetName().lowercaseString
}

func GetUppercaseNameImpl(obj:T) -> String {
    return obj.GetName().uppercaseString
}

and extensions on Int

extension Int : Named {
    func GetName() -> String {
        return "Int"
    }
}

extension Int : NamedExtension {
    // use provided implementation
    func GetLowercaseName() -> String {
        return GetLowercaseNameImpl(self)
    }
    func GetUppercaseName() -> String {
        return GetUppercaseNameImpl(self)
    }
}

and I can use

1.GetName() // result Int
1.GetUppercaseName() // result "INT"
1.GetLowercaseName() // result "int"