枚舉

• OC定義和使用枚舉

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

enum season thisSeason = seasonSpring;

• Swift定義枚舉類型

//: 定義枚舉類型,枚舉的每個成員前面加case

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

//: 定義一個枚舉變量
var season = Season.Spring
//: 再次修改值的時候可以直接 .成員, 是因為類型推導.
season = Season.Summer
season = .Summer
print(season)

Swift判斷枚舉類型

//: switch判斷枚舉類型
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")
}

//: 可以省略枚舉名
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")
}

枚舉成員類型

//: 定義枚舉,成員類型為Int
enum Direction: Int {
    case North = 0
    case South = 1
    case East = 2
    case West = 3
}

//var direction = Direction.North

//: 使用初始值來定義枚舉變量
var direction = Direction(rawValue: 1)
print(direction)

//: 可選綁定
if let dir = direction {
    switch dir {
    case .North:
        print("北")
    case .South:
        print("南")
    case .East:
        print("東")
    case .West:
        print("西")
    }
}