enums.playground

/**
 How to get a method which takes any string enumeration in Swift 2.1.
 
 Actually figured out by Carl Hill-Popper, documented by me.
 */

import UIKit

// 1) Make you some string enums.

enum Wat: String {
  case
    O,
    Hai,
    Wut
}

enum Something: String {
    case
    Boop,
    Bleep,
    Blorp
}

// 2) Make a protocol which matches the features of the enum you need to use.

protocol StringEnum {
    var rawValue: String { get }
}

// 3) Pretending these are in machine-generated files and you can't access them
//    directly to add the protocol, add the protocol using an extension.

extension Wat: StringEnum {
    //Don't actually do anything since this already conforms
    //because a Wat: String already returns a rawValue.
}

extension Something: StringEnum {
    //Don't actually do anything since this already conforms
    //because a Something: String already returns a rawValue.
}


// 4) do something which takes anything conforming to the string
func doAThingWithAStringEnum(coreDataKey: StringEnum) -> String {
    return coreDataKey.rawValue
}

print(doAThingWithAStringEnum(Wat.Hai))
// Prints "Hai"

print(doAThingWithAStringEnum(Something.Bleep))
// Prints "Bleep"

// 5) Have a 🍺 to celebrate passing arbitrary string enums to a centralized method.