Swift. Serialization of request parameters


The goal

  • In the case of passing parameters to the body of the request, the ability of declaring in the form of a [String: Any] dictionary is required.
let requestParameters = [
"method": "createUser",
"credentials": [
"login": login,
"password": password,
"age": age,
"notificationSettings": [
"notifyNews": isNotifyNews,
"notifyCabinet": isCabinetNotify
struct LoginRequest: Codable {
struct Credentials: Codable {
struct NotificationSettings: Codable {
var notifyNews: Bool
var notifyCabinet: Bool

var login: String
var password: String
var age: Int
var notificationSettings: NotificationSettings

var method: String
var credentials: Credentials
  • In the case of passing parameters as a query string, it is required that the order of elements, set during initialization won't change.
let requestParameters = [
"email": email,
"firstName": firstName,
"age": age

The solution

Let’s start serializing the parameters to the body of the request. With the CodingKeyRepresentable protocol introduced in iOS 15.4 and the type erasure technique introduced in Swift 5.6, it’s easier to encode the Any type.

where Key == String


In the first case, when it is required to pass parameters to the body of the request, the method for creating and executing the request will be as follows


Previously, before the advent of CodingKeyRepresentable and type erasure, this solution could also be programmed, only for this it was necessary to additionally create an AnyEncodable container and check the key field for compliance with the String or Int type. However, with the evolution of the platform, it became much more convenient to work with the dictionary, and developer can finally forget about the new trash request model.

  1. CodingKeyRepresentable
  2. Type erasure
  3. URLComponents
  4. URLQueryItem



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