enum CompassPoint{
? ? case north
? ? case south
? ? case east
? ? case west
} Swift中沒有默認(rèn)值 嚎幸，在C和OC中north=0嫉晶，south=1，east=2封断，west=3
enum Planet{
? ? ? ?case mercury,venus,earth,mars,jupiter,saturn,uranus,neptune
}
var directionToHead=CompassPoint.west
directionToHead= .east
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")
}
// Prints "Watch out for penguins"
enum Barcode{
? ?case upc(Int,Int,Int,Int)//條形碼
? ?case qrCode(String)//二維碼
}
var productBarcode = Barcode.upc(8,85909,51226,3)
productBarcode= .qrCode("ABCDEFGHIJKLMNOP")
switch productBarcode{
case ?.upc(let numberSystem,let manufacturer,let product,let check):
? ? ? ? ?print("UPC:\(numberSystem),\(manufacturer),\(product),\(check).")
case ?.qrCode(let productCode):
? ? ? ? ?print("QR code:\(productCode).")?
}
// Prints "QR code: ABCDEFGHIJKLMNOP."
Raw Values // 初始值
enum ?ASCIIControlCharacter:Character{
? ? ? case tab="\t"
? ? ? case lineFeed="\n"
? ? ? case carriageReturn="\r"
}
Implicitly Assigned Raw Values // 隱式分配的原始值
enum Planet:Int{
? ? ? case ?mercury=1,venus,earth,mars,jupiter,saturn,uranus,neptune
} // venus=2,后面的一次遞增
enum ?CompassPoint:String{
? ? ? ? case ?north,south,east,west
} // 默認(rèn)初始值 north = "north" south = "south" 后面雷同
let positionToFind=11
if let somePlanet = Planet(rawValue:positionToFind) ?{
? ? ? ? ? switch somePlanet{
? ? ? ? ? ? ? ? ? ? case ?.earth:
? ? ? ? ? ? ? ? ? ? ? ? ?print("Mostly harmless")
? ? ? ? ? ? ? ? ? ? default:
? ? ? ? ? ? ? ? ? ? ? ? ?print("Not a safe place for humans")
? ? ? ? ? }
}else{
? ? ? ? ?print("There isn't a planet at position\(positionToFind)")
}
// Prints "There isn't a planet at position 11"
Recursive Enumerations ?// 遞歸枚舉
enum ArithmeticExpression{
? ? ? ?case number(Int)
? ? ? ?indirect case addition(ArithmeticExpression,ArithmeticExpression)
? ? ? ?indirect case multiplication(ArithmeticExpression,ArithmeticExpression)
}
indirect enum ArithmeticExpression{
? ? ? ? case number(Int)
? ? ? ? case addition(ArithmeticExpression,ArithmeticExpression)
? ? ? ? case multiplication(ArithmeticExpression,ArithmeticExpression)
}
let five=ArithmeticExpression.number(5)
let four=ArithmeticExpression.number(4)
let sum=ArithmeticExpression.addition(five,four)
let product=ArithmeticExpression.multiplication(sum,ArithmeticExpression.number(2))
func evaluate( _ expression:ArithmeticExpression) ->Int{
? ? ? ? ? ? ?switch expression{
? ? ? ? ? ? ? ? ? case let ?.number(value):
? ? ? ? ? ? ? ? ? ? ? ? ? ?return value
? ? ? ? ? ? ? ? ? case let ?.addition(left,right):
? ? ? ? ? ? ? ? ? ? ? ? ? ?return evaluate(left) + evaluate(right)
? ? ? ? ? ? ? ? ?case let ?.multiplication(left,right):
? ? ? ? ? ? ? ? ? ? ? ? ? return evaluate(left) ?* ?evaluate(right)
? ? ? ? ? ?}
}
print(evaluate(product)) ? ? ? ? ? ? ??// Prints "18"
