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 location: String
  
  enum CodingKeys: String, CodingKey {
    case id
    case location
  }
}

let address = Address(id: 1,
                      location: "House no. 123, New Delhi, India")

let user = User(id: 1,
                name: "John",
                address: address)