Swift枚举的一些小用法总结

enum Optional<T> {
 case Some(T)
 case None
}

struct MyStruct {
  var value: Int

  init(_ value: Int?) {
    if let val = value {
      self.value = val
    } else {
      self.value = Int(INT_MAX)
    }
  }
}

class Two {
  var value1: String?
  var value2: Int?
  var value3: MyStruct?

  func setValue1(value: String?) { }
  func setValue2(value: Int?) { }
  func setValue2(value: MyStruct?) { }
}

enum ValueBind {
  case bindStringValue(str: String)
  case bindIntValue(num: Int)
  case bindModel(model: MyStruct)
}

class Two {
  var value1: String?
  var value2: Int?
  var value3: MyStruct?

  func setValueBind(value: ValueBind) {
    switch value {
    case .bindStringValue(let str):
      print(str)
    case .bindModel(let model):
      print(model.value)
    case .bindIntValue(let num)
      print(num)
    }
  }
}

enum Direction {
  case left
  case top
  case right
  case bottom
}

enum StringEnum: String {
  case hello = "hello"
  case world = "world"
}

enum IntEnum: Int {
  case one = 1
  case two = 2
}

enum CustomEnum: RawRepresentable {
  typealias RawValue = MyStruct

  case null
  case one
  case two
  
  init?(rawValue: MyStruct) {
    switch rawValue.value {
    case 1:
      self = .one
    case 2:
      self = .two
    default:
      self = .null
    }
  }

  var rawValue: MyStruct {
    switch self {
    case .one:
      return MyStruct(1)
    case .two:
      return MyStruct(2)
    default:
      return MyStruct(nil)
    }
  }
}

/*
  将枚举的 RawValue 关联为自己希望的类型
**/
associatedtype RawValue

/*
  利用自己关联的类型生成枚举的实例
**/
init?(rawValue: Self.RawValue)

/*
  将自己定义的类型的作为 RawValue 返回
**/
var rawValue: Self.RawValue { get }