//创建姓氏枚举,和Objective-C不同，Swift枚举不会默认分配值
enum Surname {
  case 张
  case 王
  case 李
  case 赵
}
//创建一个枚举类型的变量
var myName = Surname.张
//如果可以自动推断出类型 则枚举类型可以省略
myName = .李
var myName2:Surname = .王

enum Planet {
  case Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
}

switch myName {
case .张:
  print("姓氏张")
case .王:
  print("姓氏王")
case .李:
  print("姓氏李")
case .赵:
  print("姓氏赵")
}

enum Number {
  case one(count:Int)
  case two(count:Int)
  case three(count:Int)
  case four(count:Int)
}
var num = Number.one(count: 5)
switch num {
  //获取num的相关值
case Number.one(let count):
  print(count)
default:
  print(num)
}
//如果一个枚举值所有的相关中都是常量，let关键字也可以提取到括号外面
switch num {
  //获取num的相关值
case let Number.one(count):
  print(count)
default:
  print(num)
}

enum Char:String {
  case a = "A"
  case b = "B"
  case c = "C"
}
//”A“
var char = Char.a.rawValue

enum Char:Int{
  case a = 0
  case b
  case c
}
//1
var char = Char.b.rawValue

enum Char:Int{
  case a = 0
  case b
  case c
}
//1
var char = Char.b.rawValue
//b
var char2 = Char(rawValue:1)

enum Expression {
  //表示加
  case add
  //表示减
  case mul
}

enum Expression {
  //表示加
  case add(Int,Int)
  //表示减
  case mul(Int,Int)
}

var exp = Expression.add(5, 5)

enum Expression {
  //单值数据
  case num(Int)
  //表示加 indirect为递归枚举关键字
  indirect case add(Expression,Expression)
  //表示减
  indirect case mul(Expression,Expression)
}
var exp1 = Expression.num(5)
var exp2 = Expression.num(5)
var exp3 = Expression.add(exp1, exp2)
var exp4 = Expression.mul(exp1, exp3)

func expFunc(param:Expression) -> Int {
  //进行枚举判断
  switch param {
    //如果是单独数字 直接返回
  case .num(let p):
    return p
    //如果是加法 则进行递归加
  case .add(let one, let two):
    return expFunc(one)+expFunc(two)
    //如果是乘法 则进行递归乘
  case .mul(let one, let two):
    return expFunc(one)*expFunc(two)
  }
}
//50
expFunc(exp4)

indirect enum Expression {
  //单值数据
  case num(Int)
  //表示加 indirect为递归枚举关键字
  case add(Expression,Expression)
  //表示减
  case mul(Expression,Expression)
}

enum CompassPoint {
  case North
  case South
  case East
  case West
}

enum Planet {
  case Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
}

var directionToHead = CompassPoint.West 
//directionToHead是一个CompassPoint类型，可以被赋值为该类型的其他值
//当设置directionToHead的值时，他的类型是已知的，因此可以省略East的类型
directionToHead = .East

directionToHead = .South
switch directionToHead {
case .North:
  println("Lots of planets have a north")
case .South:
  println("Watch out for penguins")
case .East:
  println("Where the sun rises")
case .West:
  println("Where the skies are blue")
}
// 打印 "Watch out for penguins"

enum Barcode {
  case UPCA(Int, Int, Int)
  case QRCode(String)
}
//定义一个变量。该变量即可被赋值为3个整数，又可被赋值为一个字符串，但都是Barcode类型的枚举值
var productBarcode = Barcode.UPCA(8, 85909_51226, 3)
productBarcode = .QRCode("ABCDEFGHIJKLMNOP")

//使用switch时，case内可区分条形码种类，可使用变量或常量获得结合值
switch productBarcode {
case .UPCA(let numberSystem, let identifier, let check):
  println("UPC-A with value of \(numberSystem), \(identifier), \(check).")
case .QRCode(let productCode):
  println("QR code with value of \(productCode).")
}
// 打印 "QR code with value of ABCDEFGHIJKLMNOP."

case let .UPCA(numberSystem, identifier, check):

//原始值枚举的类型紧跟枚举名后，其成员的原始值的数据类型都是这个指定的类型
enum ASCIIControlCharacter: Character {
  case Tab = "\t"
  case LineFeed = "\n"
  case CarriageReturn = "\r"
}
//Int类型的原始值枚举成员的原始值是递增的，比如Venus的值是2，Earth的值是3
enum Planet: Int {
  case Mercury = 1, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
}
//可以通过toRaw方法获得枚举成员的原始值
let earthsOrder = Planet.Earth.toRaw()
// earthsOrder 的值是 3，数据类型是Int

//可以通过fromRaw方法获得原始值对应的枚举成员
let possiblePlanet = Planet.fromRaw(7)
// possiblePlanet 的数据类型 Planet? 值是 Planet.Uranus

//因为fromRaw的原始值可能没有对应的枚举成员，所以返回的类型是一个可选变量值
let positionToFind = 9
if let somePlanet = Planet.fromRaw(positionToFind) {
  switch somePlanet {
  case .Earth:
    println("Mostly harmless")
  default:
    println("Not a safe place for humans")
  }
} else {
  println("There isn't a planet at position \(positionToFind)")
}
// 枚举定义中没有原始值为9的成员，所以打印 "There isn't a planet at position 9"