/* プロトコルと拡張 */ protocol ExampleProtocol { var simpleDescription: String { get } mutating func adjust() } extension Int: ExampleProtocol { var simpleDescription: String { return "The number \(self)" } mutating func adjust() { self += 42 } } print("7.simpleDescription = \(7.simpleDescription)") var n : Int = 7 n.adjust() print("n.simpleDescription = \(n.simpleDescription)")