級別: ★☆☆☆☆
標籤:「iOS」「Swift 5.1 」「嵌套類型」
做者: 沐靈洛
審校: QiShare團隊
php
Swift容許定義嵌套類型,在它們所支持類型的定義中支持嵌套枚舉,類和結構。類型能夠嵌套到所需的級別。git
struct BlackjackCard {
// nested Suit enumeration
enum Suit: Character {
case spades = "♠", hearts = "♡", diamonds = "♢", clubs = "♣"
}
// nested Rank enumeration
enum Rank: Int {
case two = 2, three, four, five, six, seven, eight, nine, ten
case jack, queen, king, ace
struct Values {
let first: Int, second: Int?
}
var values: Values {
switch self {
case .ace:
return Values(first: 1, second: 11)
case .jack, .queen, .king:
return Values(first: 10, second: nil)
default:
return Values(first: self.rawValue, second: nil)
}
}
}
// BlackjackCard properties and methods
let rank: Rank, suit: Suit
var description: String {
var output = "suit is \(suit.rawValue),"
output += " value is \(rank.values.first)"
if let second = rank.values.second {
output += " or \(second)"
}
return output
}
}
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###嵌套類型的引用github
let heartsSymbol = BlackjackCard.Suit.hearts.rawValue
// heartsSymbol is "♡"
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