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

原则上,如果你不为enum的大小写使用原始值赋值,这样做是可能的:

enum RankEnum: Int {
  case Ace
  case One
  case Two
}

class RankEnumGenerator: Generator {
    var i = 0
    typealias Element = RankEnum
    func next() -> Element? {
        let r = RankEnum.fromRaw(i)
        i += 1
        return r
    }
}

extension RankEnum {
    static func enumerate() -> SequenceOf<RankEnum> {
        return SequenceOf<RankEnum>({ RankEnumGenerator() })
    }
}

for r in RankEnum.enumerate() {
    println("\(r.toRaw())")
}

其他回答

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)")
}

这篇文章是相关的https://www.swift-studies.com/blog/2014/6/10/enumerating-enums-in-swift

基本上,提议的解决方案是

enum ProductCategory : String {
     case Washers = "washers", Dryers = "dryers", Toasters = "toasters"

     static let allValues = [Washers, Dryers, Toasters]
}

for category in ProductCategory.allValues{
     //Do something
}

Swift 5解决方案:

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

// access cases like this:

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

我在比特和字节中跌跌撞撞,创建了一个扩展,后来我发现它与@rintaro的答案非常相似。它是这样使用的:

enum E : EnumCollection {
    case A, B, C
}

Array(E.cases())    // [A, B, C]

值得注意的是,它可以在任何没有关联值的enum上使用。注意,这对于没有大小写的枚举不起作用。

与@rintaro的答案一样,这段代码使用枚举的底层表示。这种表示没有文档化,将来可能会改变,这会破坏它。我不建议在生产中使用这种方法。

代码(Swift 2.2, Xcode 7.3.1,不工作在Xcode 10):

protocol EnumCollection : Hashable {}
extension EnumCollection {
    static func cases() -> AnySequence<Self> {
        typealias S = Self
        return AnySequence { () -> AnyGenerator<S> in
            var raw = 0
            return AnyGenerator {
                let current : Self = withUnsafePointer(&raw) { UnsafePointer($0).memory }
                guard current.hashValue == raw else { return nil }
                raw += 1
                return current
            }
        }
    }
}

代码(Swift 3, Xcode 8.1,不工作在Xcode 10):

protocol EnumCollection : Hashable {}
extension EnumCollection {
    static func cases() -> AnySequence<Self> {
        typealias S = Self
        return AnySequence { () -> AnyIterator<S> in
            var raw = 0
            return AnyIterator {
                let current : Self = withUnsafePointer(to: &raw) { $0.withMemoryRebound(to: S.self, capacity: 1) { $0.pointee } }
                guard current.hashValue == raw else { return nil }
                raw += 1
                return current
            }
        }
    }
}

我不知道为什么我需要typealias,但编译器抱怨没有它。

原则上,如果你不为enum的大小写使用原始值赋值,这样做是可能的:

enum RankEnum: Int {
  case Ace
  case One
  case Two
}

class RankEnumGenerator: Generator {
    var i = 0
    typealias Element = RankEnum
    func next() -> Element? {
        let r = RankEnum.fromRaw(i)
        i += 1
        return r
    }
}

extension RankEnum {
    static func enumerate() -> SequenceOf<RankEnum> {
        return SequenceOf<RankEnum>({ RankEnumGenerator() })
    }
}

for r in RankEnum.enumerate() {
    println("\(r.toRaw())")
}