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:
♠
♥
♦
♣
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
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++) {
...
}
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)")
}
我发现了一种有点俗气但更安全的方法,它不需要键入两次值或引用枚举值的内存,因此不太可能损坏。
基本上,与其使用枚举,不如创建一个具有单个实例的结构体,并将所有enum-values设置为常量。然后可以使用Mirror查询变量
public struct Suit{
// the values
let spades = "♠"
let hearts = "♥"
let diamonds = "♦"
let clubs = "♣"
// make a single instance of the Suit struct, Suit.instance
struct SStruct{static var instance: Suit = Suit()}
static var instance : Suit{
get{return SStruct.instance}
set{SStruct.instance = newValue}
}
// an array with all of the raw values
static var allValues: [String]{
var values = [String]()
let mirror = Mirror(reflecting: Suit.instance)
for (_, v) in mirror.children{
guard let suit = v as? String else{continue}
values.append(suit)
}
return values
}
}
如果使用此方法,则需要使用Suit.instance.clubs或Suit.instance.spades来获取单个值
但所有这些都太无聊了……让我们做一些事情,使它更像一个真正的enum!
public struct SuitType{
// store multiple things for each suit
let spades = Suit("♠", order: 4)
let hearts = Suit("♥", order: 3)
let diamonds = Suit("♦", order: 2)
let clubs = Suit("♣", order: 1)
struct SStruct{static var instance: SuitType = SuitType()}
static var instance : SuitType{
get{return SStruct.instance}
set{SStruct.instance = newValue}
}
// a dictionary mapping the raw values to the values
static var allValuesDictionary: [String : Suit]{
var values = [String : Suit]()
let mirror = Mirror(reflecting: SuitType.instance)
for (_, v) in mirror.children{
guard let suit = v as? Suit else{continue}
values[suit.rawValue] = suit
}
return values
}
}
public struct Suit: RawRepresentable, Hashable{
public var rawValue: String
public typealias RawValue = String
public var hashValue: Int{
// find some integer that can be used to uniquely identify
// each value. In this case, we could have used the order
// variable because it is a unique value, yet to make this
// apply to more cases, the hash table address of rawValue
// will be returned, which should work in almost all cases
//
// you could also add a hashValue parameter to init() and
// give each suit a different hash value
return rawValue.hash
}
public var order: Int
public init(_ value: String, order: Int){
self.rawValue = value
self.order = order
}
// an array of all of the Suit values
static var allValues: [Suit]{
var values = [Suit]()
let mirror = Mirror(reflecting: SuitType.instance)
for (_, v) in mirror.children{
guard let suit = v as? Suit else{continue}
values.append(suit)
}
return values
}
// allows for using Suit(rawValue: "♦"), like a normal enum
public init?(rawValue: String){
// get the Suit from allValuesDictionary in SuitType, or return nil if that raw value doesn't exist
guard let suit = SuitType.allValuesDictionary[rawValue] else{return nil}
// initialize a new Suit with the same properties as that with the same raw value
self.init(suit.rawValue, order: suit.order)
}
}
你现在可以做
let allSuits: [Suit] = Suit.allValues
or
for suit in Suit.allValues{
print("The suit \(suit.rawValue) has the order \(suit.order)")
}
然而,要获得一个单一,你仍然需要使用SuitType.instance.spades或SuitType.instance.hearts。为了更加直观,您可以向Suit添加一些允许您使用Suit.type的代码。*而不是SuitType.instance.*
public struct Suit: RawRepresentable, Hashable{
// ...your code...
static var type = SuitType.instance
// ...more of your code...
}
您现在可以使用Suit.type.diamonds而不是SuitType.instance。diamonds,或者Suit.type.clubs而不是SuitType.instance.clubs
enum Rank: Int
{
case Ace = 0
case Two, Three, Four, Five, Six, Seve, Eight, Nine, Ten
case Jack, Queen, King
case Count
}
enum Suit : Int
{
case Spades = 0
case Hearts, Diamonds, Clubs
case Count
}
struct Card
{
var rank:Rank
var suit:Suit
}
class Test
{
func makeDeck() -> Card[]
{
let suitsCount:Int = Suit.Count.toRaw()
let rankCount:Int = Rank.Count.toRaw()
let repeatedCard:Card = Card(rank:Rank.Ace, suit:Suit.Spades)
let deck:Card[] = Card[](count:suitsCount*rankCount, repeatedValue:repeatedCard)
for i:Int in 0..rankCount
{
for j:Int in 0..suitsCount
{
deck[i*suitsCount+j] = Card(rank: Rank.fromRaw(i)!, suit: Suit.fromRaw(j)!)
}
}
return deck
}
}
根据Rick的回答:这要快5倍
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
}
Swift 4 + 2。
从Swift 4.2 (Xcode 10)开始,只需将协议一致性添加到CaseIterable中,就可以从allCases中受益。要添加这个协议一致性,你只需要在某个地方写:
extension Suit: CaseIterable {}
如果枚举是你自己的,你可以直接在声明中指定一致性:
enum Suit: String, CaseIterable { case spades = "♠"; case hearts = "♥"; case diamonds = "♦"; case clubs = "♣" }
然后下面的代码将打印所有可能的值:
Suit.allCases.forEach {
print($0.rawValue)
}
与早期Swift版本的兼容性(3。X和4.x)
如果您需要支持Swift 3。x或4.0,你可以通过添加以下代码来模仿Swift 4.2的实现:
#if !swift(>=4.2)
public protocol CaseIterable {
associatedtype AllCases: Collection where AllCases.Element == Self
static var allCases: AllCases { get }
}
extension CaseIterable where Self: Hashable {
static var allCases: [Self] {
return [Self](AnySequence { () -> AnyIterator<Self> in
var raw = 0
var first: Self?
return AnyIterator {
let current = withUnsafeBytes(of: &raw) { $0.load(as: Self.self) }
if raw == 0 {
first = current
} else if current == first {
return nil
}
raw += 1
return current
}
})
}
}
#endif