Dictionary extension to allow using enums (or any RawableType) as keys in a dictionary

enum-keys.swift

protocol RawableKey {
    associatedtype RawType
    var rawValue: RawType { get }
}


extension Dictionary {
    subscript<K: RawableKey>(enumKey: K) -> Value? {
        get {
            if let key = enumKey.rawValue as? Key {
                return self[key]
            }
            return nil
        }
        set {
            if let key = enumKey.rawValue as? Key {
                self[key] = newValue
            }
        }
    }
}

enum Keys: String {
    case foo, bar, baz
}

extension Keys: RawableKey { }

var d = [String : Any]()

d[Keys.foo] = "foo"
d[Keys.baz] = "bar"
d[Keys.bar] = "baz"