Swift Examples - Nested Types

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The Swift Programming Language Examples

源码在 GitHub：https://github.com/gewill/The-Swift-Programming-Language-2.1-Examples

Playground ->

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// : Playground - noun: a place where people can play

import UIKit

//: 嵌套类型（Nested Types）



//嵌套让我们可以为常数生成一个命名空间（namespace）。例如：我们可以使用Constants.FoursquareApi.BaseUrl来访问Foursquare的BaseUrl常数，这样会使得数据可读性更高，并为相关的常数提供一系列封装。
//http://geek.csdn.net/news/detail/58593
import Foundation
struct Constants {
    struct FoursquareApi {
        static let BaseUrl = "https://api.foursquare.com/v2/"
    }
    struct TwitterApi {
        static let BaseUrl = "https://api.twitter.com/1.1/"
    }
    struct Configuration {
        static let UseWorkaround = true
    }
}


//上面的嵌套是不错的实践，当然扑克牌作为例子是非常合适的。

struct BlackjackCard {
    // 嵌套的 Suit 枚举
    enum Suit: Character {
        case Spades = "♠", Hearts = "♡", Diamonds = "♢", Clubs = "♣"
    }
    
    // 嵌套的 Rank 枚举
    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 的属性和方法
    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
    }
}

BlackjackCard(rank: .Ace, suit: .Spades).description
let heartsSymbol = BlackjackCard.Suit.Hearts.rawValue