Good ideas

AlamofireRequests.swift

// definitions
typealias RequestOptions = (HTTPMethod, Set<HeaderOption>, String, String, Encodable?)

protocol RequestOptionsConvertible {
  func asRequestOptions() throws -> RequestOptions
}

// "rigging"
enum PaymentMappings: RequestOptionsConvertible {
  case .listAvailablePaymentMethods(PaymentMethodsRequest)
  case .disablePaymentMethod(DisablePaymentMethodRequest)
  case .makePayment(PaymentRequest)
  case .completePayment(PaymentFinalisationRequest)
  case .getPaymentStatus(Int)
  
  static let BASE_URL = ...
     
  func asRequestOptions() throws -> RequestOptions {
    switch self {
      case .listAvailablePaymentMethods(let parameters):
        return (.post, [.useApiKey, .useAuthToken], Self.BASE_URL, "/payment-methods", parameters)
      case .disablePaymentMethod(let parameters):
        return (.post, [.useApiKey, .useAuthToken], Self.BASE_URL, "/payment-methods/disable", parameters)
      case .makePayment(let parameters):
        return (.post, [.useApiKey, .useAuthToken], Self.BASE_URL, "/payments", parameters)
      case .completePayment(let parameters):
        return (.post, [.useApiKey, .useAuthToken], Self.BASE_URL, "/payments/details", parameters)
      case .getStatus(let orderNumber):
        return (.get, [.useApiKey], Self.BASE_URL, "/payments/\(orderNumber)/status", .none)
    }
  }
}

// usage
let (method, headerOptions, baseURL, path, parameters) = req.asRequestOptions()
// prep request
//...
AF.request(...)