Custom handler using custom serializer

DataRequest+TwoDecodableResponseHandler.swift

extension DataRequest {

    /// Decodes the response to a type `T` or` APIError`.
    ///
    /// NB: The serializer used `TwoDeodableResponseSerializer` doesn't throw though Alamofire
    /// response serializer expects to receive a `DataResponse`. All errors/failures are converted to an `APIError`.
    ///
    /// - Parameters:
    ///   - t: Type to decode to
    ///   - queue: `DispatchQueue` to dispatch `completionHandler`
    ///   - errorCode: code to signal error when to fetch `APIError`
    ///   - completionHandler: Handler called on completion
    @discardableResult func responseDecodable<T: Decodable>(queue: DispatchQueue = DispatchQueue.global(qos: .userInitiated), of t: T.Type, errorCode: StatusCode, completionHandler: @escaping (Result<T, APIError>) -> Void) -> Self {
        return response(queue: .main, responseSerializer: TwoDecodableResponseSerializer<T>(errorCode: errorCode)) { response in
            switch response.result {
            case .success(let result):
                completionHandler(result)
            case .failure(let error):
                completionHandler(.failure(.init(error: error)))
            }
        }
    }
}