Codable.swift

import UIKit

class Person: Codable {
    let givenName: String
    let surName: String
    let middleName: String?
    let gender: Gender

    init(givenName: String, surName: String, middleName: String?, gender: Gender) {
        self.givenName = givenName
        self.surName = surName
        self.middleName = middleName
        self.gender = gender
    }

    enum Gender: String, Codable {
        init(from decoder: Decoder) throws {
            let container = try decoder.singleValueContainer()
            let rawValue = try container.decode(String.self)

            self = Gender.init(rawValue: rawValue) ?? Gender.unknown
        }

        case male
        case female
        case unknown
    }
}

let data = "{ \"givenName\": \"Viktor\", \"surName\": \"Rutberg\", \"gender\": \"android\" }".data(using: .utf8)
let person = try? JSONDecoder().decode(Person.self, from: data!)

print(person?.givenName)
print(person?.surName)
print(person?.middleName)
print(person?.gender.rawValue)