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
其他的解决方法都是可行的,但它们都假设了可能的等级和花色的数量,或者第一和最后的等级是什么。的确,在可预见的未来,一副纸牌的布局可能不会有太大变化。然而,一般来说,编写尽可能少假设的代码会更简洁。我的解决方案:
我已经在Suit枚举中添加了一个原始类型,所以我可以使用Suit(rawValue:)来访问Suit案例:
enum Suit: Int {
case Spades = 1
case Hearts, Diamonds, Clubs
func simpleDescription() -> String {
switch self {
case .Spades:
return "spades"
case .Hearts:
return "hearts"
case .Diamonds:
return "diamonds"
case .Clubs:
return "clubs"
}
}
func color() -> String {
switch self {
case .Spades:
return "black"
case .Clubs:
return "black"
case .Diamonds:
return "red"
case .Hearts:
return "red"
}
}
}
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.rawValue)
}
}
}
在Card的createDeck()方法实现的下面。init(rawValue:)是一个可失败的初始化式,返回一个可选值。通过在两个while语句中展开并检查它的值,不需要假设Rank或Suit情况的数量:
struct Card {
var rank: Rank
var suit: Suit
func simpleDescription() -> String {
return "The \(rank.simpleDescription()) of \(suit.simpleDescription())"
}
func createDeck() -> [Card] {
var n = 1
var deck = [Card]()
while let rank = Rank(rawValue: n) {
var m = 1
while let suit = Suit(rawValue: m) {
deck.append(Card(rank: rank, suit: suit))
m += 1
}
n += 1
}
return deck
}
}
下面是如何调用createDeck方法:
let card = Card(rank: Rank.Ace, suit: Suit.Clubs)
let deck = card.createDeck()
其他回答
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]
如果您仍然想为Rank和Suit使用枚举,这里有一个不那么神秘的例子。如果您想使用for-in循环遍历每个对象,只需将它们收集到一个Array中。
标准52张牌的例子:
enum Rank: Int {
case Ace = 1, Two, Three, Four, Five, Six, Seven, Eight, Nine, Ten, Jack, Queen, King
func name() -> String {
switch self {
case .Ace:
return "ace"
case .Jack:
return "jack"
case .Queen:
return "queen"
case .King:
return "king"
default:
return String(self.toRaw())
}
}
}
enum Suit: Int {
case Diamonds = 1, Clubs, Hearts, Spades
func name() -> String {
switch self {
case .Diamonds:
return "diamonds"
case .Clubs:
return "clubs"
case .Hearts:
return "hearts"
case .Spades:
return "spades"
default:
return "NOT A VALID SUIT"
}
}
}
let Ranks = [
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 Suits = [
Suit.Diamonds,
Suit.Clubs,
Suit.Hearts,
Suit.Spades
]
class Card {
var rank: Rank
var suit: Suit
init(rank: Rank, suit: Suit) {
self.rank = rank
self.suit = suit
}
}
class Deck {
var cards = Card[]()
init() {
for rank in Ranks {
for suit in Suits {
cards.append(Card(rank: rank, suit: suit))
}
}
}
}
var myDeck = Deck()
myDeck.cards.count // => 52
enum Rank: Int {
...
static let ranks = (Rank.Ace.rawValue ... Rank.King.rawValue).map{Rank(rawValue: $0)! }
}
enum Suit {
...
static let suits = [Spades, Hearts, Diamonds, Clubs]
}
struct Card {
...
static func fullDesk() -> [Card] {
var desk: [Card] = []
for suit in Suit.suits {
for rank in Rank.ranks {
desk.append(Card(rank: rank,suit: suit))
}
}
return desk
}
}
这个怎么样?
有一种聪明的方法,尽管令人沮丧,但它说明了两种不同类型的枚举之间的区别。
试试这个:
func makeDeck() -> Card[] {
var deck: Card[] = []
var suits: Suit[] = [.Hearts, .Diamonds, .Clubs, .Spades]
for i in 1...13 {
for suit in suits {
deck += Card(rank: Rank.fromRaw(i)!, suit: suit)
}
}
return deck
}
交易是,一个由数字(原始值)支持的枚举是隐式显式有序的,而一个没有数字支持的枚举是显式隐式无序的。
例如,当我们给枚举值数字时,语言足够狡猾,可以找出数字的顺序。 另一方面,如果我们不给它任何顺序,当我们尝试迭代这些值时,语言就会举起双手说:“是的,但你想先执行哪个??”
其他可以做到这一点(迭代无序枚举)的语言可能是相同的语言,其中所有内容实际上都是一个地图或字典,你可以迭代地图的键,无论是否有任何逻辑顺序。
诀窍是给它提供一些显式排序的东西,在这个例子中,suit的实例在数组中按照我们想要的顺序。一旦你这么说,霉霉就会说“你为什么不一开始就这么说呢?”
另一个简写技巧是在fromRaw函数上使用强制操作符。这说明了关于枚举的另一个“陷阱”,即可能传入的值的范围通常大于枚举的范围。例如,如果我们说Rank.fromRaw(60),就不会返回值,所以我们使用了语言的可选特性,在我们开始使用可选特性的地方,很快就会出现强制。(或者交替if let结构,这对我来说仍然有点奇怪)
实验内容是: 实验
在Card中添加一个方法,用于创建一副完整的牌,每一副牌都是rank和花色的组合。
因此,除了添加方法之外,没有修改或增强给定的代码(并且没有使用还没有教过的东西),我想出了这个解决方案:
struct Card {
var rank: Rank
var suit: Suit
func simpleDescription() -> String {
return "The \(rank.simpleDescription()) of \(suit.simpleDescription())"
}
func createDeck() -> [Card] {
var deck: [Card] = []
for rank in Rank.Ace.rawValue...Rank.King.rawValue {
for suit in Suit.Spades.rawValue...Suit.Clubs.rawValue {
let card = Card(rank: Rank(rawValue: rank)!, suit: Suit(rawValue: suit)!)
//println(card.simpleDescription())
deck += [card]
}
}
return deck
}
}
let threeOfSpades = Card(rank: .Three, suit: .Spades)
let threeOfSpadesDescription = threeOfSpades.simpleDescription()
let deck = threeOfSpades.createDeck()