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

我的解决方案是声明一个包含所有枚举可能性的数组。所以for循环可以遍历所有这些。

//Function inside struct Card
static func generateFullDeck() -> [Card] {
    let allRanks = [Rank.Ace, Rank.Two, Rank.Three, Rank.Four, Rank.Five, Rank.Six, Rank.Seven, Rank.Eight, Rank.Nine, Rank.Ten, Rank.Jack, Rank.Queen, Rank.King]
    let allSuits = [Suit.Hearts, Suit.Diamonds, Suit.Clubs, Suit.Spades]
    var myFullDeck: [Card] = []

    for myRank in allRanks {
        for mySuit in allSuits {
            myFullDeck.append(Card(rank: myRank, suit: mySuit))
        }
    }
    return myFullDeck
}

//actual use:
let aFullDeck = Card.generateFullDeck()    //Generate the desired full deck

var allDesc: [String] = []
for aCard in aFullDeck {
    println(aCard.simpleDescription())    //You'll see all the results in playground
}

其他回答

更新代码:Swift 4.2/Swift 5

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

按问题访问输出:

for suitKey in Suit.allCases {
    print(suitKey.rawValue)
}

输出:

♠
♥
♦
♣

CaseIterable:提供其所有值的集合。 符合CaseIterable协议的类型通常是没有关联值的枚举。当使用CaseIterable类型时,您可以通过使用该类型的allCases属性访问该类型的所有案例的集合。

对于访问case,我们使用。allcases。更多信息请点击https://developer.apple.com/documentation/swift/caseiterable

在Swift中,枚举类型可以像EnumType一样访问。案例:

let tableView = UITableView(frame: self.view. view)UITableViewStyle.Plain)

大多数情况下,只有当您有几个选项可以使用,并且确切地知道在每个选项上要做什么时,才会使用枚举类型。

在处理枚举类型时,使用for-in结构没有太大意义。

你可以这样做,例如:

func sumNumbers(numbers : Int...) -> Int {
    var sum = 0

    for number in numbers{
        sum += number
    }

    return sum
}

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?)

你可以试着像这样列举

enum Planet: String {
    case Mercury
    case Venus
    case Earth
    case Mars

    static var enumerate: [Planet] {
        var a: [Planet] = []
        switch Planet.Mercury {
            case .Mercury: a.append(.Mercury); fallthrough
            case .Venus: a.append(.Venus); fallthrough
            case .Earth: a.append(.Earth); fallthrough
            case .Mars: a.append(.Mars)
        }
    return a
    }
}

Planet.enumerate // [Mercury, Venus, Earth, Mars]

有时,您可能会处理具有底层原始整数类型的枚举类型,这种类型在整个软件开发生命周期中都会发生变化。下面是一个很适合这种情况的例子:

public class MyClassThatLoadsTexturesEtc
{
    //...

    // Colors used for gems and sectors.
    public enum Color: Int
    {
        // Colors arranged in order of the spectrum.
        case First = 0
        case Red, Orange, Yellow, Green, Blue, Purple, Pink
        // --> Add more colors here, between the first and last markers.
        case Last
    }

    //...

    public func preloadGems()
    {
        // Preload all gems.
        for i in (Color.First.toRaw() + 1) ..< (Color.Last.toRaw())
        {
            let color = Color.fromRaw(i)!
            loadColoredTextures(forKey: color)
        }
    }

    //...
}