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,let y):

    print("终点(\(x),\(y))")

case .center(let x,let y):

    print("中点(\(x),\(y))")

}