De- "stringifying" a stringly typed enumeration.

Enums.swift

import UIKit

struct TrafficLight {
    
    enum TrafficLightState: Int {
        case proceed = 1
        case proceedWithCaution = 13
        case stop = 9
        
        var lightColor: UIColor {
            switch self {
            case .proceed:
                return .green
            case .proceedWithCaution:
                return .yellow
            case .stop:
                return .red
                
            }
        }
    }
    
    var streetName: String
    var state: TrafficLightState
}

let firstLight = TrafficLight(streetName: "Main", state: .stop)

print(firstLight.state.rawValue)
print(firstLight.state.lightColor)