Protocol func returning Self

Question

I have a protocol P that returns a copy of the object:

protocol P {
    func copy() -> Self
}

and a class C that implements P:

Answer 1

With Swift 2, we can use protocol extensions for this.

protocol Copyable {
    init(copy:Self)
}

extension Copyable {
    func copy() -> Self {
        return Self.init(copy: self)
    }
}