🔰nested types

Swift ⟩ types ⟩ nested types ⟩

🔴 主題

• extension of nested types

• to nest or not to nest❓

📗 參考

• AppCoda ⟩ Nested Objects in Swift (善用 Swift 的嵌套物件功能)

👁️ 預覽

struct Blackjack {

    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
    }
}

// extension can have nested types
extension Blackjack {

    // ⭐️ nested type: `Blackjack.Suit`
    enum Suit: Character {
        case spades = "♠", hearts = "♡", diamonds = "♢", clubs = "♣"
    }

    // ⭐️ nested type: `Blackjack.Rank`
    enum Rank: Int {
    
        case two = 2, three, four, five, six, seven, eight, nine, ten
        case jack, queen, king, ace
        
        // ⭐️ nested type: `Blackjack.Rank.Values`
        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)
            }
        }
    }
}

💈範例

📘 手冊

• Swift ⟩ Nested Types

👥 相關

• Extensions can define nested types.

• can have extension of nested types.