https://qiita.com/hikaruna/items/7d2e919be0bc93bf3f45 を `RawRepresentable` で実装

enumState.swift

class Mario {
    enum State: RawState {
        case normal = "normal"
        case big = "big"
        case fire = "fire"
        case dead = "dead"
    }
    var state: State = .normal
    var name: String { return "\(state.rawValue.name)マリオ" }
    func hitEnemy() { state.rawValue.hitEnemy(self) }
}

private protocol MarioStateBehavior {
    var name: String { get }
    func hitEnemy(_ mario: Mario)
}

protocol Factory {
    init(factory: Self)
}

extension Factory {
    init(factory: Self) {
        self = factory
    }
}

class RawState: MarioStateBehavior, RawRepresentable, Equatable, ExpressibleByStringLiteral, Factory {
    // MarioStateBehavior
    var name: String { fatalError("unreachable") }
    func hitEnemy(_ mario: Mario) { fatalError("unreachable") }

    // RawRepresentable
    var rawValue: String
    required init(rawValue: String) { self.rawValue = rawValue }

    // Equatable
    static func == (lhs: RawState, rhs: RawState) -> Bool { return lhs.rawValue == rhs.rawValue }

    // ExpressibleByStringLiteral
    required convenience init(stringLiteral value: String) {
        switch value {
        case "normal": self.init(factory: Normal(rawValue: value))
        case "big": self.init(factory: Big(rawValue: value))
        case "fire": self.init(factory: Fire(rawValue: value))
        case "dead": self.init(factory: Dead(rawValue: value))
        default: fatalError("unreachable")
        }
    }
}

class Normal: RawState {
    override var name: String { return "チビ" }
    override func hitEnemy(_ mario: Mario) {
        print("死ぬ")
        mario.state = .dead
    }
}

class Big: RawState {
    override var name: String { return "スーパー" }
    override func hitEnemy(_ mario: Mario) {
        print("チビマリオになる")
        mario.state = .normal
    }
}

class Fire: RawState {
    override var name: String { return "ファイアー" }
    override func hitEnemy(_ mario: Mario) {
        print("チビマリオになる")
        mario.state = .normal
    }
}

class Dead: RawState {
    override var name: String { return "死んだ" }
    override func hitEnemy(_ mario: Mario) {
        print("死ぬ")
    }

}

// 以下使用例

let mario = Mario()

mario.name //=> "チビマリオ"
mario.hitEnemy() //=> print 死ぬ
mario.state // dead

mario.state = .big
mario.name //=> "スーパーマリオ"
mario.hitEnemy() //=> print チビマリオになる
mario.state // normal