Swift枚举详解

enum SomeEnumeration {
    // 在这里定义枚举
} 

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

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

var directionToHead = CompassPoint.West 

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")
}
// 输出"Watch out for penguins” 

let somePlanet = Planet.Earth
switch somePlanet {
    case .Earth:
        println("Mostly harmless")
    default:
        println("Not a safe place for humans")
}
// 输出 "Mostly harmless" 

enum Barcode {
    case UPCA(Int, Int, Int)
    case QRCode(String)
} 

var productBarcode = Barcode.UPCA(8, 85909_51226, 3) 

productBarcode = .QRCode("ABCDEFGHIJKLMNOP") 

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).") } 

switch productBarcode {
    case let .UPCA(numberSystem, identifier, check):
        println("UPC-A with value of \(numberSystem), \(identifier), \(check).")
    case let .QRCode(productCode):
        println("QR code with value of \(productCode).")
}
// 输出 "QR code with value of ABCDEFGHIJKLMNOP.” 

enum ASCIIControlCharacter: Character {
    case Tab = "\t"
    case LineFeed = "\n"
    case CarriageReturn = "\r"
} 

enum Planet: Int {
    case Mercury = 1, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
} 

let earthsOrder = Planet.Earth.toRaw()
//eathsOrder is 3 

let possiblePlanet = Planet.fromRaw(7)
// possiblePlanet is of type Planet? and equals Planet.Uranus” 

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)")
}
// 输出 "There isn't a planet at position 9”