编辑代码

enum CompassPoint {
    case north
    case south
    case east
    case west
}

enum Planet {
    case mercury, venus, earth, mars, jupiter, saturn, uranus, neptune
}
//缩写

var hello = Planet.venus
switch hello {
    case .mercury:
        print("hello")
    default:
        print("失败")
}


var directionToHead = CompassPoint.west

directionToHead = .south
switch directionToHead {
case .north:
    print("Lots of planets have a north")
case .south:
    print("Watch out for penguins")
case .east:
    print("Where the sun rises")
case .west:
    print("Where the skies are blue")
}
// 打印“Watch out for penguins”


let somePlanet = Planet.earth
switch somePlanet {
case .earth:
    print("Mostly harmless")
default:
    print("Not a safe place for humans")
}
//switch需要穷尽所有可能性，除非使用default语句
// 打印“Mostly harmless”

enum Beverage: CaseIterable {
    case coffee, tea, juice
}
let numberOfChoices = Beverage.allCases.count
print("\(numberOfChoices) beverages available")
// 打印“3 beverages available”

for beverage in Beverage.allCases {
    print(beverage)
}




enum Barcode {
    case upc(Int, Int, Int, Int)
    case qrCode(String)
}

var productBarcode = Barcode.upc(8, 85909, 51226, 3)

//productBarcode = .qrCode("ABCDEFGHIJKLMNOP")



switch productBarcode {
case let .upc(numberSystem, manufacturer, product, check):
    print("UPC: \(numberSystem), \(manufacturer), \(product), \(check).")
case let .qrCode(productCode):
    print("QR code: \(productCode).")
}
// 打印“QR code: ABCDEFGHIJKLMNOP.”