DecodableJSONExample.swift

let serviceOneJSON = """
{
    "user_name": "Mukesh",
    "user_tagline": "Experience is the name everyone gives to their mistakes",
    "id": 1
}
""".data(using: .utf8)!

let serviceTwoJSON = """
{
    "full_name": "Mukesh Mandora",
    "status": "In order to be irreplaceable, one must always be different",
    "user_id": 12
}
""".data(using: .utf8)!

struct UserOfProduct: Decodable {
    var name: String?
    var userId: Int?
    var tagline: String?

    enum ServiceOneCodingKeys: String, CodingKey {
        case name = "user_name"
        case userId = "id"
        case tagline = "user_tagline"
    }

    enum ServiceTwoCodingKeys: String, CodingKey {
        case name = "full_name"
        case userId = "user_id"
        case tagline = "status"
    }

    init(from decoder: Decoder) throws {
        // Service One JSON Container
        let containerForServiceOne = try decoder.container(keyedBy: ServiceOneCodingKeys.self)
        userId = try containerForServiceOne.decodeIfPresent(Int.self,
                                                            forKey: .userId)
        name = try containerForServiceOne.decodeIfPresent(String.self,
                                                          forKey: .name)
        tagline = try containerForServiceOne.decodeIfPresent(String.self,
                                                             forKey: .tagline)

        // Check any one param which is required to not be nil in this case
        // userId, based on that we will take decision to decode from another container
        guard userId == nil else {
            return
        }

        // Service Two JSON Container
        let containerForServiceTwo = try decoder.container(keyedBy: ServiceTwoCodingKeys.self)
        userId = try containerForServiceTwo.decodeIfPresent(Int.self,
                                                            forKey: .userId)
        name = try containerForServiceTwo.decodeIfPresent(String.self,
                                                          forKey: .name)
        tagline = try containerForServiceTwo.decodeIfPresent(String.self,
                                                             forKey: .tagline)

        // Failure send crash report to find this unknown keys
        guard userId != nil else {
            fatalError("Decooding error")
        }
    }
}
let userObjectFromServiceOne = try! JSONDecoder().decode(UserOfProduct.self, from: serviceOneJSON)
print("User Name from Service One, \(userObjectFromServiceOne.name ?? "")")
print("User Tagline from Service One, \(userObjectFromServiceOne.tagline ?? "")")

let userObjectFromServiceTwo = try! JSONDecoder().decode(UserOfProduct.self, from: serviceTwoJSON)
print("User Name from Service Two, \(userObjectFromServiceTwo.name ?? "")")
print("User Tagline from Service Two, \(userObjectFromServiceTwo.tagline ?? "")")