如何为这个Json创建模型？

Question

我是iOS swift3的初学者。实际上我在从Json创建我自己的模型时遇到了一个问题。我的Json有三个数组，分别是CountryList，CityList和PortList。 CountryList具有countryID和countryName。 CityList有countryId，cityId和cityName。 PortList有countryId，cityId和portName。现在，我希望在tableView中显示数据，该表具有基于城市的国家和城市的国家和城市。我想创建一个模型，该模型在该国家/地区拥有国家和城市，在该城市拥有港口。如果有人帮助我，我将非常感激。 谢谢.. 这是我到目前为止所写的代码......

struct Country {

var countryId: String!
var countryName: String!

init(countryId: String, countryName: String){
    self.countryId = countryId
    self.countryName = countryName
}}
struct City {

var countryId: String!
var cityId : String!
var cityName: String!

init(countryId: String, cityId: String, cityName: String){
    self.countryId = countryId
    self.cityId = cityId
    self.cityName = cityName

}}
struct Ports {

var countryId: String!
var cityId : String!
var portName: String!

init(countryId: String, cityId: String, portName: String){
    self.countryId = countryId
    self.cityId = cityId
    self.portName = portName

}}

我创建了三个结构来保存我从Json获得的数据。 我在viewController中的代码看起来像这样。

class ViewController: UIViewController {

var countriesList = [Country]()
var citiesList = [City]()
var portsList = [Ports]()

var cities = [String]()

override func viewDidLoad() {
    super.viewDidLoad()
    getData()

}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()

}

func getData(){

    let url = URL(string: "http://54.186.73.184:8081/api/v0/portlist/search/1")
    var request = URLRequest(url: url!)
    request.httpMethod = "GET"

    let task = URLSession.shared.dataTask(with: request) { (data, response, error) in

        if error == nil{

            do{
                let data = try JSONSerialization.jsonObject(with: data!, options: JSONSerialization.ReadingOptions.allowFragments) as! [String: AnyObject]
               // print(data)

                let countriesData = data["country_list"] as!  [[String: AnyObject]]
                //print(countriesData)

                for ids in countriesData{

                    let id = ids["_id"] as! [String: AnyObject]

                    let cId = id["_id"] as! String



                    let country = id["country"] as! String

                    //  self.countries.append(country)


                    let countrydata = Country(countryId: cId, countryName: country)
                    self.countriesList.append(countrydata)



                    for country in self.countriesList{
                        let cId = country.countryId

                        let cityList = self.getAllCities(withCountryId: cId!)


                    }

                }



                let cityData = data["city_list"] as!  [AnyObject]
                for ids in cityData{

                    let id = ids["_id"] as! [String: AnyObject]
                    // print(id)
                    let countryId = id["country_id"] as! String
                    // print(countryId)


                    let cityId = id["_id"] as! String
                    // print(cityId)

                    let city = id["city"] as! String
                    // print(city)





                    let cityData = City(countryId: countryId, cityId: cityId, cityName: city)

                    self.citiesList.append(cityData)
                    //   print(self.citiesList)
            }


               let portData = data["port_list"] as!  [AnyObject]
                for ids in portData{

                    let id = ids["_id"] as! [String: AnyObject]
                    // print(id)

                    let countryId = id["country_id"] as! String
                    //  print(countryId)

                    let cityId = id["city_id"] as! String
                    //  print(cityId)

                    let port = id["ports"] as! String
                    //  print(port)

                    let portData = Ports(countryId: countryId, cityId: cityId, portName: port)
                    self.portsList.append(portData)
                    //  print(self.portsList)

                }

                }catch{

                print(error)
            }
          }
        }
       task.resume()
    }

func getAllCities(withCountryId id: String) -> [AnyObject]{

    // print("citiesList---------\(self.citiesList)")

    for city in self.citiesList{

        if (city.countryId == id){

          self.cities.append(city.cityName)

        }
    }

    return [self.cities as AnyObject]

}}

但我得到空城列表。 希望有人找到创建符合我要求的模型的想法。 谢谢..