swift_032（Swift enum枚举高级使用范例）

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

import UIKitvar str = "Hello, playground"enum Movement {    case Left    case Right    case Top    case Bottom}let aMovement = Movement.Leftswitch aMovement {case .Left:    print("left")default:    print("Unknow")}if case .Left = aMovement {    print("Left")}if .Left == aMovement {    print("Left")}enum Season: Int {    case Spring = 0    case Summer = 1    case Autumn = 2    case Winter = 3}enum House: String {    case ZhangSan = "I am zhangsan"    case LiSi = "I am lisi"}let zs = House.ZhangSanprint(zs.rawValue)enum Constants: Double {    case π = 3.14159    case e = 2.71828    case φ = 1.61803398874    case λ = 1.30357}let pai = Constants.πprint(pai.rawValue)enum CompassPoint: String {    case North, South, East, West}let n = CompassPoint.Northprint(n.rawValue)let s = CompassPoint(rawValue: "South");enum VNodeFlags : UInt32 {    case Delete = 0x00000001    case Write = 0x00000002    case Extended = 0x00000004    case Attrib = 0x00000008    case Link = 0x00000010    case Rename = 0x00000020    case Revoke = 0x00000040    case None = 0x00000080}enum Character {        enum Weapon {        case Bow        case Sword        case Lance        case Dagger    }        enum Helmet {        case Wooden        case Iron        case Diamond    }        case Thief    case Warrior    case Knight}let character = Character.Thieflet weapon = Character.Weapon.Bowlet helmet = Character.Helmet.Ironstruct Scharacter {    enum CharacterType {        case Thief        case Warrior        case Knight    }        enum Weapon {        case Bow        case Sword        case Lance        case Dagger    }        let type: CharacterType    let weapon: Weapon}let sc = Scharacter(type: .Thief, weapon: .Bow)print(sc.type)enum Trade {    case Buy(stock: String, amount: Int)    case Sell(stock: String, amount: Int)}let trade = Trade.Buy(stock: "Car", amount: 100)if case let Trade.Buy(stock, amount) = trade {    print("buy \(amount) of \(stock)")}enum Trade0 {    case Buy(String, Int)    case Sell(String, Int)}let trade0 = Trade0.Buy("Car0", 100)if case let Trade0.Buy(stock, amount) = trade0 {    print("buy \(amount) of \(stock)")}enum Wearable {    enum Weight: Int {        case Light = 2    }        enum Armor: Int {        case Light = 2    }        case Helmet(weight: Weight, armor: Armor)            func attributes() -> (weight: Int, armor: Int) {        switch self {        case .Helmet(let w, let a):            return (weight: w.rawValue * 2, armor: a.rawValue * 4)          }    }}let test = Wearable.Helmet(weight: .Light, armor: .Light).attributes()print(test)enum Device {    case iPad, iPhone, AppleTV, AppleWatch    func introduced() -> String {        switch self {        case .AppleTV: return "\(self) was introduced 2006"        case .iPhone: return "\(self) was introduced 2007"        case .iPad: return "\(self) was introduced 2010"        case .AppleWatch: return "\(self) was introduced 2014"        }    }}print (Device.iPhone.introduced())enum Device1 {    case iPad, iPhone    var year: Int {        switch self {        case .iPad:            return 2010        case .iPhone:            return 2007    }    }}let iPhone = Device1.iPhoneprint(iPhone.year)enum Device2 {    case AppleWatch        static func fromSlang(term: String) -> Device2? {        if term == "iWatch" {            return .AppleWatch        }        return nil    }}print(Device2.fromSlang(term: "iWatch") ?? "nil")enum TriStateSwitch {    case Off, Low, High        mutating func next() {        switch self {        case .Off:            self = .Low        case .Low:            self = .High        case .High:            self = .Off    }    }}var state = TriStateSwitch.Low // 必须使用varstate.next()state.next()protocol CustomStringConvertible {    var description: String { get }}enum Trade1: CustomStringConvertible {    case Buy, Sell    var description: String {        switch self {        case .Buy:            return "We're buying something"        case .Sell:            return "We're selling something"    }    }}let t1 = Trade1.Buy.descriptionprotocol AccountCompatible {    var remainingFunds: Int { get }    mutating func addFunds(amount: Int) throws    mutating func removeFunds(amount: Int) throws}enum Account {    case Empty    case Funds(remaining: Int)        enum ErrorInfo: Error {        case OverDraft(amount: Int)    }        var remainingFunds: Int {        switch self {        case .Empty:            return 0        case .Funds(let remaining):            return remaining    }    }}extension Account: AccountCompatible {    mutating func addFunds(amount: Int) throws {        var newAmount = amount        if case let .Funds(remaining) = self {            newAmount += remaining        }                if newAmount < 0 {            throw Account.ErrorInfo.OverDraft(amount: newAmount)        }else if newAmount == 0 {            self = .Empty        }else {            self = .Funds(remaining: newAmount)        }    }        mutating func removeFunds(amount: Int) throws {        try self.addFunds(amount: amount * -1)    }}var account = Account.Funds(remaining: 20)try? account.addFunds(amount: 20)print("add: ", account.remainingFunds)try? account.removeFunds(amount: 15)print ("remove 1: ", account.remainingFunds)do {    try account.removeFunds(amount: 55)}catch (let errorInfo)  {    print(errorInfo)}print ("remove 2: ",  try? account.removeFunds(amount: 55))

来源：Swift 中枚举高级用法及实践