Level: ★☆☆ Tag: “iOS” “Swift 5.1” “nested type” author: Muling Luo review: QiShare team

Swift allows the definition of nested types, supporting nested enumerations, classes, and structures in the definition of the types they support. Types can be nested to the desired level.

Nested types are used

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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### nested type references

let heartsSymbol = BlackjackCard.Suit.hearts.rawValue
// heartsSymbol is "♡"
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