SwiftCopyableProtocol.swift

protocol Copyable {
    associatedtype V
    func copy() -> V
    func setup(v: V) -> V
}

class One: Copyable {
    typealias V = One
    var name: String?
    
    func copy() -> V {
        let instance = One()
        return setup(instance)
    }
    
    func setup(v: V) -> V {
        v.name = self.name
        return v
    }
}

class Two: One {
    var id: Int?
    override func copy() -> Two {
        let instance = Two()
        return setup(instance)
    }
    
    func setup(v: Two) -> Two {
        super.setup(v)
        v.id = self.id
        return v
    }
}

extension Array where Element: Copyable {
    func clone() -> [Element.V] {
        var copiedArray: [Element.V] = []
        for element in self {
            copiedArray.append(element.copy())
        }
        return copiedArray
    }
}

let array = [One(), Two()]
let copied = array.clone()
print("\(array)")
print("\(copied)")