Swift -- enum 繼承 protocol

原文地址連結：http://blog.csdn.net/duanyipeng/article/details/32338575

Apple官方文件：The Swift Programming Language
Protocols and Extensions一節的小節練習，要求自行定義一個enumeration列舉型別，並且遵循ExampleProtocol協議：

　　

protocol ExampleProtocol {
    var simpleDescription: String { get }
     mutating func adjust()
}

　　// 列舉繼承協議

enum EnumConformToProtocol: ExampleProtocol {
    case First(String), Second(String), Third(String)

    var simpleDescription: String {
        get {
            switch self {
            case let .First(text):
                return text
            case let .Second(text):
                return text
            case let .Third(text):
                return text
            default:
                return "get error"
            }
        }
        set {
            switch self {
            case let .First(text):
                self = .First(newValue)
            case let .Second(text):
                self = .Second(newValue)
            case let .Third(text):
                self = .Third(newValue)
            }
        }
    }
    mutating func adjust() {
        switch self {
        case let .First(text):
            self = .First(text + " (first case adjusted)")
        case let .Second(text):
            self = .Second(text + " (second case adjusted)")
        case let .Third(text):
            self = .Third(text + " (third case adjusted)")
        }
    }
}
var enumConformToProtocolTest = EnumConformToProtocol.First("FirstVal")
enumConformToProtocolTest.simpleDescription
enumConformToProtocolTest.adjust()
enumConformToProtocolTest.simpleDescription

enumConformToProtocolTest = EnumConformToProtocol.Third("ThirdVal")
enumConformToProtocolTest.simpleDescription
enumConformToProtocolTest.adjust()
enumConformToProtocolTest.simpleDescription

var e = EnumConformToProtocol.Second("Hello")
var text = e.simpleDescription
e.simpleDescription = "Adios"
text = e.simpleDescription
e.adjust()
text = e.simpleDescription