Swift --- rawValue

举个例子：

    enum Rank: Int {
        
        case ace = 1
        
        case two, three, four, five, six, seven, eight, nine, ten
        
        case jack, queen, king
        
        func simpleDescription() -> String {
            
            switch self {
                
            case .ace:
                
                return "ace"
            
            case .jack:
                
                return "jack"
                
            case .queen:
                
                return "queen"
                
            case .king:
                
                return "king"
                
            default:

                return String(self.rawValue)
                
            }
        }
    }

override func viewDidLoad() {
    
    super.viewDidLoad()
    
    let ace = Rank.ace
    
    let aceRawValue = ace.rawValue
    
    if aceRawValue == 1 {
        
        print("Yes")
    }
}

init?(rawValue:)

    override func viewDidLoad() {
        
        super.viewDidLoad()

        if let convert = Rank(rawValue: 5){
            
            print("\(convert.simpleDescription())")
        }
    }
控制台打印：5