Swift 枚举字符串和整数

Question

我有这样一种情况，我正在尝试对某些数据进行二进制解码，而数据类型既有数值也有字符串值和名称。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这两个 "things" 字符串和数值封装到枚举结构中，或者我需要做一些有点 struct/class 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)

这将打印 True Track Angle

同样，我知道这可以用结构或 class 来完成，但我对枚举特别感兴趣

或者另一个例子：

/// 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 "read" 将枚举作为字符串？我很确定答案是否定的。

Answer 1

我想这对我来说会成功。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

你考虑过使用字典吗？

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

请注意，数字代码不必有序或连续。在其声明中具体说明字典的类型可防止以下代码段中出现大量警告或错误。

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")
}

我还没有找到一个简洁的方法来获取名称的代码，但是这样做了：

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

你当然会把它装扮成一个函数。您没有自动获得的是您的轨道类型的内部名称，但您需要一个吗？上面的行以某种方式为你做了。

Answer 3

在 Swift 4.2 中，这可以使用 CaseIterable 来完成。一、比较简洁的做法是如下

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 4

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 5

总结@Jeef 的回答和@NobodyNada 的评论，这是一个解决方案

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

Swift 枚举字符串和整数

Swift enum both a string and an int

enums

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