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

您可以通过实现ForwardIndexType协议来迭代枚举。

ForwardIndexType协议要求您定义一个继任者()函数来逐级遍历元素。

enum Rank: Int, ForwardIndexType {
    case Ace = 1
    case Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten
    case Jack, Queen, King

    // ... other functions

    // Option 1 - Figure it out by hand
    func successor() -> Rank {
        switch self {
            case .Ace:
              return .Two
            case .Two:
              return .Three

            // ... etc.

            default:
              return .King
        }
    }

    // Option 2 - Define an operator!
    func successor() -> Rank {
        return self + 1
    }
}

// NOTE: The operator is defined OUTSIDE the class
func + (left: Rank, right: Int) -> Rank {
    // I'm using to/from raw here, but again, you can use a case statement
    // or whatever else you can think of

    return left == .King ? .King : Rank(rawValue: left.rawValue + right)!
}

在开或闭范围内迭代(..<或…)将在内部调用继任者()函数,允许你这样写:

// Under the covers, successor(Rank.King) and successor(Rank.Ace) are called to establish limits
for r in Rank.Ace...Rank.King {
    // Do something useful
}

其他回答

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)
}

更新到Swift 2.2+

func iterateEnum<T: Hashable>(_: T.Type) -> AnyGenerator<T> {
    var i = 0
    return AnyGenerator {
        let next = withUnsafePointer(&i) {
            UnsafePointer<T>($0).memory
        }
        if next.hashValue == i {
            i += 1
            return next
        } else {
            return nil
        }
    }
}

它更新了Swift 2.2表单@Kametrixom的答案

Swift 3.0+(非常感谢@Philip)

func iterateEnum<T: Hashable>(_: T.Type) -> AnyIterator<T> {
    var i = 0
    return AnyIterator {
        let next = withUnsafePointer(&i) {
            UnsafePointer<T>($0).pointee
        }
        if next.hashValue == i {
            i += 1
            return next
        } else {
            return nil
        }
    }
}

(改进Karthik Kumar的回答)

这个解决方案是使用编译器来保证你不会错过一个case。

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

    static var enumerate: [Suit] {
        switch Suit.spades {
        // make sure the two lines are identical ^_^
        case        .spades, .hearts, .diamonds, .clubs:
            return [.spades, .hearts, .diamonds, .clubs]
        }
    }
}

它花了我一点,而不仅仅是一个方法在结构像swift书调用,但我在枚举中设置了下一个函数。我会使用一个协议,我不知道为什么,但有秩设置为int混乱。

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.toRaw())
        }
    }
    mutating func next() -> Rank {
        var rank = self
        var rawrank = rank.toRaw()
        var nrank: Rank = self
        rawrank = rawrank + 1
        if let newRank = Rank.fromRaw(rawrank) {
            println("\(newRank.simpleDescription())")
            nrank = newRank
        } else {
            return self
        }
        return nrank
    }
}

enum Suit {
    case Spades, Hearts, Diamonds, Clubs
    func color() -> String {
        switch self {
        case .Spades, .Clubs:
            return "black"
        default:
            return "red"
        }
    }
    func simpleDescription() -> String {
        switch self {
        case .Spades:
            return "spades"
        case .Hearts:
            return "hearts"
        case .Diamonds:
            return "diamonds"
        case .Clubs:
            return "clubs"
        }
    }
    mutating func next() -> Suit {
        switch self {
        case .Spades:
            return Hearts
        case .Hearts:
            return Diamonds
        case .Diamonds:
            return Clubs
        case .Clubs:
            return Spades
        }
    }
}

struct Card {
    var rank: Rank
    var suit: Suit
    func deck() -> Card[] {
        var tRank = self.rank
        var tSuit = self.suit
        let tcards = 52 // we start from 0
        var cards: Card[] = []
        for i in 0..tcards {
            var card = Card(rank: tRank, suit: tSuit)
            cards.append(card)
            tRank = tRank.next()
            tSuit = tSuit.next()
        }
        return cards
    }
    func simpleDescription() -> String {
        return "The \(rank.simpleDescription()) of \(suit.simpleDescription())"
    }
}

var card = Card(rank: .Ace, suit: .Spades)
var deck = card.deck()

我使用了一些常识,但这可以通过将花色乘以等级来轻松纠正(如果你没有使用标准的桥牌,你必须相应地改变枚举,如果基本上只是通过不同的枚举进行步骤)。为了节省时间,我使用了ranks rawValues,如果你愿意,你也可以为西装做同样的事情。然而,这个例子没有它,所以我决定在不改变suit rawValue的情况下找出它

在Swift 3中,当底层枚举有rawValue时,你可以实现Strideable协议。优点是不像其他建议那样创建值数组,并且标准的Swift“for in”循环工作,这是一个很好的语法。

// "Int" to get rawValue, and Strideable so we can iterate
enum MyColorEnum: Int, Strideable {
    case Red
    case Green
    case Blue
    case Black

    // required by Strideable
    typealias Stride = Int

    func advanced(by n:Stride) -> MyColorEnum {
        var next = self.rawValue + n
        if next > MyColorEnum.Black.rawValue {
            next = MyColorEnum.Black.rawValue
        }
        return MyColorEnum(rawValue: next)!
    }

    func distance(to other: MyColorEnum) -> Int {
        return other.rawValue - self.rawValue
    }

    // just for printing
    func simpleDescription() -> String {
        switch self {
        case .Red: return "Red"
        case .Green: return "Green"
        case .Blue: return "Blue"
        case .Black: return "Black"
        }
    }
}

// this is how you use it:
for i in MyColorEnum.Red ... MyColorEnum.Black {
    print("ENUM: \(i)")
}