swift 4.0 枚举

枚举

import UIKit


indirect enum Arithemtic{
    case number(Int)
    case addition(Arithemtic,Arithemtic)
    case multiplication(Arithemtic,Arithemtic)
}

//枚举 swift中没有默认的整形值
enum SomeEnumeration{
    case north
    case south
    case east
    case west
}

//多个成员值要写在同一行，用逗号隔开
enum Plant{
    case mercury,earth,mars
}

//关联值
enum BarCode {
    case upc(Int,Int,Int,Int) //根据数字识别商品
    case qrCode(String) //根据代码识别商品
}

//枚举的原始值
enum ASCIIControlChar : Character{
    case tab = "\t"
    case lineFeed = "\n"
    case carriageReturn = "\r"
}

//字符串的默认值是枚举值本身  数字依次往后+1
enum Planet:Int {
    case mercury = 1, venus,earth,mars
}


class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        
        
        var directionToHead = SomeEnumeration.west
        directionToHead = .east
        
        switch directionToHead {
        case .north:
            print("north")
        case .south:
            print("south")
        case .east:
            print("east")
        default:
            print("没有这个方向")
        }
        
        //关联值
        var productBar = BarCode.upc(8, 8, 3, 4)
        productBar = .qrCode("ABCDE")
        
        //获取枚举变量的原始值
        let earthsOrder = Plant.earth.hashValue
        print(earthsOrder)
        
        //创建递归表达式
        let five = Arithemtic.number(5)
        let four = Arithemtic.number(4)
        let sum = Arithemtic.addition(five, four)
        let product = Arithemtic.multiplication(sum, five)
        // (5 + 4) * 5
        
        
    }
}