UserAddressModel.swift

struct User: Encodable {
  let id: Int
  let name: Encodable
  let address: Address
  
  enum CodingKeys: String, CodingKey {
    case id
    case name
  }
}

struct Address: Encodable {
  let id: Int
  let address: String
  let city: String
  let state: String
  let country: String
  
  enum CodingKeys: String, CodingKey {
    case id
    case address
    case city
    case state
    case country
  }
}

let address = Address(id: 1,
                      address: "House no. 123",
                      city: "New Delhi",
                      state: "Delhi",
                      country: "India")
let user = User(id: 1,
                name: "John",
                address: address)