Swift--09枚举类型

//声明枚举类型

enum Direction {

#if false

case north

case south

case east

case west

#else

case north,south,east,west

#endif

}

//初始化未指明类型时需要：类型.枚举值

var dir = Direction.east

//当变量类型已知时无需写类型：.枚举值

dir = .east //东

var dir2: Direction = .south

switch dir {

case .north:

print("北")

case .south:

print("南")

case .east:

print("东")

case .west:

print("西")

}

//原始值

enum Week: Int {

case monday = 100,tuesday,wednesday,thursday,friday,saturday,sunday

}

//在没有指定枚举值使用的数据类型时，无法获取原始值

print(Week.friday.rawValue)//104

//将一个原始值转换枚举变量，会得到一个可选类型的变量(因为可能会失败)

let dayOne = Week(rawValue: 102)

if let day = dayOne {

print(day)//wednesday

}

//枚举关联值

enum Point {

case start(x: Double,y: Double)

case end(x: Double,y: Double)

case center(x: Double,y: Double)

}

var point = Point.start(x: 0,y: 0)

point = .end(x: 10,y: 10)

point = .center(x: 5,y: 5)

switch point {

case .start(let x,let y):

print("起点((x),(y))")

case .end(let x,19)"> print("终点((x),(y))")

case .center(let x,19)"> print("中点((x),(y))")

}

（编辑：李大同）

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