Swift枚举字符串和int

Question

我有一种情况，我正在尝试对某些数据进行二进制解码，并且数据类型同时具有数值和字符串值以及名称。我正在考虑使用枚举，例如：

enum TARGET_TRACK_TYPE : String {
    case TT_INVALID          = "Invalid"
    case TT_TRUE_TRACK_ANGLE = "True Track Angle"
    case TT_MAGNETIC         = "Magnetic"
    case TT_TRUE             = "True"
}

不过我也知道：

TT_INVALID = 0 和TT_TRUE_TRACK_ANGLE = 1 等。有没有一种简单的方法可以将字符串和数值这两个“东西”封装到一个枚举结构中，或者我需要制作某种结构/类来处理这个?

我想我想做一些类似的事情

let a = TARGET_TRACK_TYPE.rawValue(value: 2) println(a)

将打印True Track Angle

再次，我知道这可以通过结构或类来完成，但我对枚举特别感兴趣

或者再举个例子：

/// Emitter Category is defined in section 3.5.1.10 of the GDL90 Spec
struct EmitterCategory {

let category : Int

func getString() -> String {

    switch(category) {
    case 0:
        return "No aircraft type information";
    case 1:
        return "Light";
    case 2:
        return "Smalle";
    case 3:
        return "Large";
    case 4:
        return "High Vortex Large";
    case 5:
        return "Heavy";
    case 6:
        return "Highly Manuverable";
    case 7:
        return "Rotorcraft";
    case 8:
        return "(Unassigned)";
    case 9:
        return "Glider/sailplane";
    case 10:
        return "Ligther than air";
    case 11:
        return "Parachutist/sky diver";
    case 12:
        return "Ultra light/hang glider/paraglider";
    case 13:
        return "(Unassigned)";
    case 14:
        return "Unmanned aerial vehicle";
    case 15:
        return "Space/transatmospheric vehicle";
    case 16:
        return "(Unassigned)";
    case 17:
        return "Surface vehicle - emergency vehicle";
    case 18:
        return "Surface vehicle - service vehicle";
    case 19:
        return "Point obstacle";
    case 20:
        return "Cluster Obstacle";
    case 21:
        return "Line Obstacle";
    default:
        return "(reserved)";
    }
}
}

有没有办法将此结构重构为枚举，以便我用整数值构造枚举但我将枚举“读取”为字符串？我很确定答案是否定的。

Answer 1

我认为这会为我做这件事。谢谢你自己.. :)

protocol GDL90_Enum  {
      var description: String { get }
}

enum TARGET_ADDRESS_TYPE : Int, GDL90_Enum {
   case ADSB_ICAO_ADDRESS = 0
   case ADSB_SELF_ADDRESS = 1
   case TISB_ICAO = 2
   case TISB_TRACK_ID = 3
   case SURFACE_VEHICLE = 4
   case GROUND_STATION = 5

   var description: String {
      switch self {
   case .ADSB_ICAO_ADDRESS:
      return "ADS-B with ICAO address"
   case .ADSB_SELF_ADDRESS:
      return "ADS-B with Self-assigned address"
   case .TISB_ICAO:
      return "TIS-B with ICAO address"
   case .TISB_TRACK_ID:
         return "TIS-B with track file ID"
   case .SURFACE_VEHICLE:
         return "Surface Vehicle"
   case .GROUND_STATION:
         return "Ground Station Beacon"
   default:
         return "Reserved"
      }
   }
}

Answer 2

在 Swift 4.2 中，这可以使用 CaseIterable 来完成。一、比较简洁的方法是做如下

enum Directions: String, CaseIterable {
    case north, south, east, west

    static var asArray: [Directions] {return self.allCases}

    func asInt() -> Int {
        return Directions.asArray.firstIndex(of: self)!
    }
}

print(Directions.asArray[2])
// prints "east\n"

print(Directions.east.asInt())
// prints "2\n"

print(Directions.east.rawValue)
// prints "east\n"

Answer 3

你应该使用 RawRepresentable

@objc enum AppEvent:Int, RawRepresentable  {
    case appLaunch
    case homeScreen

    public typealias RawValue = String

    public var rawValue: RawValue {
        switch self {
        case .appLaunch                      : return "appLaunch"
        case .homeScreen                    : return "homeScreen"
    }

    public init?(rawValue: RawValue) {
        switch rawValue {
        case "appLaunch"                    : self = .appLaunch
        case "homeScreen"                   : self = .homeScreen 
    }

Answer 4

您是否考虑过使用字典？

 let targetTrackDict: [Int: String] =
      [99: "Invalid",
       1: "True Track Angle",
       2: "Magnetic",
       5: "True"]

请注意，数字代码不必是有序的或连续的。在声明中具体说明字典的类型可以防止以下 sn-ps 中出现很多警告或错误。

获取代码的名称很容易：

var code = 2
if let name = targetTrackDict[code] {
  print("\(name) has code \(code)")
} else {
  print("\(code) is not a valid track type")
}

我还没有找到一种获取名称代码的简洁方法，但可以这样做：

let magneticCode = targetTrackDict.first(where: 
    {key, value in value == "Magnetic"})?.key
// returns an optional

你当然会把它打扮成一个函数。您不会自动获得轨道类型的内部名称，但您需要一个吗？上面的代码在某种程度上为你做了。

Answer 5

总结@Jeef 的回答和@NobodyNada 的评论，这里有一个解决方案

public enum Animal: Int, CustomStringConvertible {
    case Dog, Cat

    public var description: String {
        switch self.rawValue {
        case 0: return "Dog"
        case 1: return "Cat"
        default: return ""
        }
    }
}

var animal = Animal.Dog
print(animal) // Dog