enum Suit: String {
    case spades = "♠"
    case hearts = "♥"
    case diamonds = "♦"
    case clubs = "♣"
}

例如,我怎么做这样的事情:

for suit in Suit {
    // do something with suit
    print(suit.rawValue)
}

结果示例:

♠
♥
♦
♣

当前回答

对不起,我的回答是具体到我如何在我需要做的事情中使用这篇文章。对于那些无意中遇到这个问题的人,寻找一种方法在枚举中找到一个case,这是一种方法(Swift 2新增):

编辑:小写驼峰现在是Swift 3 enum值的标准

// From apple docs: If the raw-value type is specified as String and you don’t assign values to the cases explicitly, each unassigned case is implicitly assigned a string with the same text as the name of that case.

enum Theme: String
    {
    case white, blue, green, lavender, grey
    }

func loadTheme(theme: String)
    {
    // this checks the string against the raw value of each enum case (note that the check could result in a nil value, since it's an optional, which is why we introduce the if/let block
    if let testTheme = Theme(rawValue: theme)
        {
        // testTheme is guaranteed to have an enum value at this point
        self.someOtherFunction(testTheme)
        }
    }

对于那些对枚举感到疑惑的人来说,本页上给出的答案包括一个包含所有枚举值的数组的静态var/let是正确的。最新的苹果tvOS示例代码包含了完全相同的技术。

也就是说,他们应该在语言中构建一个更方便的机制(苹果,你在听吗?)

其他回答

对不起,我的回答是具体到我如何在我需要做的事情中使用这篇文章。对于那些无意中遇到这个问题的人,寻找一种方法在枚举中找到一个case,这是一种方法(Swift 2新增):

编辑:小写驼峰现在是Swift 3 enum值的标准

// From apple docs: If the raw-value type is specified as String and you don’t assign values to the cases explicitly, each unassigned case is implicitly assigned a string with the same text as the name of that case.

enum Theme: String
    {
    case white, blue, green, lavender, grey
    }

func loadTheme(theme: String)
    {
    // this checks the string against the raw value of each enum case (note that the check could result in a nil value, since it's an optional, which is why we introduce the if/let block
    if let testTheme = Theme(rawValue: theme)
        {
        // testTheme is guaranteed to have an enum value at this point
        self.someOtherFunction(testTheme)
        }
    }

对于那些对枚举感到疑惑的人来说,本页上给出的答案包括一个包含所有枚举值的数组的静态var/let是正确的。最新的苹果tvOS示例代码包含了完全相同的技术。

也就是说,他们应该在语言中构建一个更方便的机制(苹果,你在听吗?)

我使用了下面的方法,假设我知道哪个是Rank enum中的最后一个值,所有的Rank在Ace之后都有增量值

我喜欢这种方式,因为它干净,小,容易理解

 func cardDeck() -> Card[] {
     var cards: Card[] = []
     let minRank = Rank.Ace.toRaw()
     let maxRank = Rank.King.toRaw()

     for rank in minRank...maxRank {
         if var convertedRank: Rank = Rank.fromRaw(rank) {
             cards.append(Card(rank: convertedRank, suite: Suite.Clubs))
             cards.append(Card(rank: convertedRank, suite: Suite.Diamonds))
             cards.append(Card(rank: convertedRank, suite: Suite.Hearts))
             cards.append(Card(rank: convertedRank, suite: Suite.Spades))
         }
    }

    return cards
}

如果你给枚举一个原始的Int值,它将使循环更容易。

例如,你可以使用anyGenerator来获得一个可以枚举你的值的生成器:

enum Suit: Int, CustomStringConvertible {
    case Spades, Hearts, Diamonds, Clubs
    var description: String {
        switch self {
        case .Spades:   return "Spades"
        case .Hearts:   return "Hearts"
        case .Diamonds: return "Diamonds"
        case .Clubs:    return "Clubs"
        }
    }
    static func enumerate() -> AnyGenerator<Suit> {
        var nextIndex = Spades.rawValue
        return anyGenerator { Suit(rawValue: nextIndex++) }
    }
}
// You can now use it like this:
for suit in Suit.enumerate() {
    suit.description
}
// or like this:
let allSuits: [Suit] = Array(Suit.enumerate())

然而,这看起来像一个相当常见的模式,如果我们可以通过简单地遵循协议使任何枚举类型可枚举,这不是很好吗?有了Swift 2.0和协议扩展,现在我们可以了!

简单地添加到你的项目:

protocol EnumerableEnum {
    init?(rawValue: Int)
    static func firstValue() -> Int
}
extension EnumerableEnum {
    static func enumerate() -> AnyGenerator<Self> {
        var nextIndex = firstRawValue()
        return anyGenerator { Self(rawValue: nextIndex++) }
    }
    static func firstRawValue() -> Int { return 0 }
}

现在,任何时候你创建一个枚举(只要它有一个Int原始值),你可以通过遵循协议使它可枚举:

enum Rank: Int, EnumerableEnum {
    case Ace, Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Jack, Queen, King
}
// ...
for rank in Rank.enumerate() { ... }

如果你的枚举值不以0开头(默认值),重写firstRawValue方法:

enum DeckColor: Int, EnumerableEnum {
    case Red = 10, Blue, Black
    static func firstRawValue() -> Int { return Red.rawValue }
}
// ...
let colors = Array(DeckColor.enumerate())

最后一个Suit类,包括用更标准的CustomStringConvertible协议替换simpleDescription,看起来像这样:

enum Suit: Int, CustomStringConvertible, EnumerableEnum {
    case Spades, Hearts, Diamonds, Clubs
    var description: String {
        switch self {
        case .Spades:   return "Spades"
        case .Hearts:   return "Hearts"
        case .Diamonds: return "Diamonds"
        case .Clubs:    return "Clubs"
        }
    }
}
// ...
for suit in Suit.enumerate() {
    print(suit.description)
}

Swift 3语法:

protocol EnumerableEnum {
    init?(rawValue: Int)
    static func firstRawValue() -> Int
}

extension EnumerableEnum {
    static func enumerate() -> AnyIterator<Self> {
        var nextIndex = firstRawValue()

        let iterator: AnyIterator<Self> = AnyIterator {
            defer { nextIndex = nextIndex + 1 }
            return Self(rawValue: nextIndex)
        }

        return iterator
    }

    static func firstRawValue() -> Int {
        return 0
    }
}

这看起来像一个黑客,但如果你使用原始值,你可以这样做

enum Suit: Int {  
    case Spades = 0, Hearts, Diamonds, Clubs  
 ...  
}  

var suitIndex = 0  
while var suit = Suit.fromRaw(suitIndex++) {  
   ...  
}  

另一个解决方案:

enum Suit: String {
    case spades = "♠"
    case hearts = "♥"
    case diamonds = "♦"
    case clubs = "♣"

    static var count: Int {
        return 4   
    }

    init(index: Int) {
        switch index {
            case 0: self = .spades
            case 1: self = .hearts
            case 2: self = .diamonds
            default: self = .clubs
        }
    }
}

for i in 0..<Suit.count {
    print(Suit(index: i).rawValue)
}