Swift enum both a string and an int - swift

Question

I have a situation where I'm trying to do binary decoding of some data and the data types have both a numerical value and a string value and a name. I was thinking of using an enum such as:
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"
}
However I also know that:
TT_INVALID = 0 and TT_TRUE_TRACK_ANGLE = 1, etc. Is there an easy way to encapsulate both these "things" the string and the numerical value into an enum construct or do i need to make some sort of struct/class to handle this?
I guess I'd like to do something like
let a = TARGET_TRACK_TYPE.rawValue(value: 2)
println(a)
which would print True Track Angle
Again, I know this can be done with a struct or a class but I'm specifically interested in the enum
Or for another example:
/// 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)";
}
}
}
Is there a way to refactor this struct into an enum such that I construct the enum with an integer value but I "read" the enum as a string? I'm pretty sure the answer is no.

Answer 1

I think this will do it for me. Thank you self.. :)
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

With Swift 4.2 this can be done using CaseIterable. One, relatively concise way is to do the following
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

You should use 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

Have you considered using a dictionary?
let targetTrackDict: [Int: String] =
[99: "Invalid",
1: "True Track Angle",
2: "Magnetic",
5: "True"]
Note the number codes don't have to be ordered or contiguous. Being specific about the dictionary's type in its declaration prevents a lot of warnings or errors in the following snippets.
Getting the name for a code is easy:
var code = 2
if let name = targetTrackDict[code] {
print("\(name) has code \(code)")
} else {
print("\(code) is not a valid track type")
}
I haven't found a tidy way of getting the code for a name, but this does it:
let magneticCode = targetTrackDict.first(where:
{key, value in value == "Magnetic"})?.key
// returns an optional
and you would of course dress it up as a function. What you don't get automatically is an internal name for your track type, but do you need one? And the line above does it for you in a way.

Answer 5

Summing up #Jeef's answer and #NobodyNada's comment, here's a solution
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