苹果公司推出的新编程语言Swift简介和入门教程

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enum Suit {
    case Spades, Hearts, Diamonds, Clubs
        func simpleDescription() -> String {
        switch self {
            case .Spades:
                return "spades"
            case .Hearts:
                return "hearts"
            case .Diamonds:
                return "diamonds"
            case .Clubs:
                return "clubs"
        }
    }
}
let hearts = Suit.Hearts
let heartsDescription = hearts.simpleDescription()
除了可以关联方法，枚举还支持在其成员上关联值，同一枚举的不同成员可以有不同的关联的值：
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enum ServerResponse {
    case Result(String, String)
    case Error(String)
}
let success = ServerResponse.Result("6:00 am", "8:09 pm")
let failure = ServerResponse.Error("Out of cheese.")
switch success {
    case let .Result(sunrise, sunset):
        let serverResponse = "Sunrise is at (sunrise) and sunset is at (sunset)."
    case let .Error(error):
        let serverResponse = "Failure... (error)"
}

 

5.2结构

Swift使用struct关键字创建结构。结构支持构造器和方法这些类的特性。结构和类的最大区别在于：结构的实例按值传递（passed by value），而类的实例按引用传递（passed by reference）。

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struct Card {
    var rank: Rank
    var suit: Suit
    func simpleDescription() -> String {
        return "The (rank.simpleDescription()) of (suit.simpleDescription())"
    }
}
let threeOfSpades = Card(rank: .Three, suit: .Spades)
let threeOfSpadesDescription = threeOfSpades.simpleDescription()