Swift 基础笔记 - 枚举

枚举

• OC定义和使用枚举

//OC 枚举:
enum season {
  seasonSpring,
  seasonSummer,
  seasonAutumn,
  seasonWinter
};

enum season thisSeason = seasonSpring;

• Swift定义枚举类型

//: 定义枚举类型,枚举的每个成员前面加case

enum Season {
    case Spring
    case Summer
    case Autumn
    case Winter   
}

//: 定义一个枚举变量
var season = Season.Spring
//: 再次修改值的时候可以直接 .成员, 是因为类型推导.
season = Season.Summer
season = .Summer
print(season)

Swift判断枚举类型

//: switch判断枚举类型
switch season {
case Season.Spring:
    print("春天")
case Season.Summer:
    print("夏天")
case Season.Autumn:
    print("秋天")
case Season.Winter:
    print("冬天")
}

//: 可以省略枚举名
var season2 = Season.Spring
switch season2 {
case .Spring:
    print("春天")
case .Summer:
    print("夏天")
case .Autumn:
    print("秋天")
case .Winter:
    print("冬天")
}

枚举成员类型

//: 定义枚举,成员类型为Int
enum Direction: Int {
    case North = 0
    case South = 1
    case East = 2
    case West = 3
}

//var direction = Direction.North

//: 使用初始值来定义枚举变量
var direction = Direction(rawValue: 1)
print(direction)

//: 可选绑定
if let dir = direction {
    switch dir {
    case .North:
        print("北")
    case .South:
        print("南")
    case .East:
        print("东")
    case .West:
        print("西")
    }
}