How to use Non-Exhaustive Enums in Swift

enum Example: Int {
    case one = 1
    case two = 2
    case three = 3
}
 
// Exhaustive
switch number {
    case .one:
        print("One")
    case .two:
        print("Two")
    case .three:
        print("Three")
}
 
// Non-Exhaustive
switch number {
    case .one:
        print("One")
    default:
        print("Catch All")
}

// This ENUM is in Swift currently, but the proposal states that this is to be used with C ENUMs.
enum ServerResponseCodes: Int {
 
    case OK = 200
    case Created = 201
    case Accepted = 202
    case NoContent = 204
    //case ResetContent = 205
 
    case MovedPermanently = 301
    case Found = 302
    case SeeOther = 303
    //case NotModified = 304
    //case UseProxy = 305
 
    case BadRequest = 400
    case Unauthorized = 401
    //case PaymentRequired = 402
    //case Forbidden = 403
    //case NotFound = 404
    //case MethodNotAllowed = 405
    //case NotAcceptable = 406
    //case RequestTimeout = 408
 
    case InternalServerError = 500
    case NotImplemented = 501
    case BadGateway = 502
    case ServiceUnavaiable = 503
    //case GatewayTimeout = 504
    //case HTTPVersionNotSupported = 505
}
 
// -------------------------------------------- //
 
// It is now a source-compatible change to add a case to a non-frozen enum (whether imported from C or defined in the standard library).
// It is not a source-compatible change to add a case to a frozen enum.
// It is still not a source-compatible change to remove a case from a public enum (frozen or non-frozen).
// It is a source-compatible change to change a non-frozen enum into a frozen enum, but not vice versa.
func getResponseStatus(responseCode: ServerResponseCodes) {
    // Swift 4.2 - 5.0 Non-Exaustive Enum Switch Statement
    #if swift(>=4.2)
        switch responseCode {
        case .OK:
            print("OK")
        case .Created:
            print("Created")
        case .Accepted:
            print("Accepted")
        case .NoContent:
            print("No Content")
        case .MovedPermanently:
            print("Moved Permanently")
        case .Found:
            print("Found")
        case .SeeOther:
            print("See Other")
        case .BadRequest:
            print("Bad Request")
        case .Unauthorized:
            print("Unauthorized")
        case .InternalServerError:
            print("Internal Server Error")
        case .NotImplemented:
            print("Not Implemented")
        case .BadGateway:
            print("Bad Gateway")
 
        // Emits a warning: Switch must be exhaustive
        @unknown default:
 
        // Does not emit a warning at all when a new case is added
        //default:
            // If any of these were added in our library.
            //case PaymentRequired = 402
            //case Forbidden = 403
            //case NotFound = 404
            //case MethodNotAllowed = 405
            print("Catch all for cases that could have been addd.")
            print("Emits a warning if new cases are added to the enum.")
        }
    // Swift 4.1 Enum Switch Statement
    // The Switch below results in an error
    #elseif swift(>=4.1)
        switch responseCode {
        case .OK:
            print("OK")
        case .Created:
            print("Created")
        case .Accepted:
            print("Accepted")
        case .NoContent:
            print("No Content")
        case .MovedPermanently:
            print("Moved Permanently")
        case .Found:
            print("Found")
        case .SeeOther:
            print("See Other")
        case .BadRequest:
            print("Bad Request")
        case .Unauthorized:
            print("Unauthorized")
        case .InternalServerError:
            print("Internal Server Error")
        case .NotImplemented:
            print("Not Implemented")
//     If all cases are switched through in an exhaustive manner, a default case is not needed.
//     Adding a new case to the enum results in: error: switch must be exhaustive
//        default:
//            print("Default Fall Through")
        }
    #endif
}