Extract User Data from remote Web server

How to extract the following from data object

idNumber firstName lastName emailAddress mobileNumber

to be displayed in label?

here's the http post request of my code

private func goToUrl(_ stringURL: String) {
    // Prepare URL
    let url = URL(string: stringURL)
    guard let requestUrl = url else { fatalError() }
     
    // Prepare URL Request Object
    var request = URLRequest(url: requestUrl)
    request.httpMethod = "POST"
     
    // Set HTTP Request header
    request.setValue("application/json", forHTTPHeaderField: "Content-Type")
    request.setValue("application/x-www-form-urlencoded", forHTTPHeaderField: "Content-Type")
    request.setValue("1088", forHTTPHeaderField: "Content-Length")
     
    // HTTP Parameters which will be sent in HTTP Request body
    let postString = "userID=\(useridTextField.text ?? "")&password=\(passwordTextField.text ?? "")"
     
    // Set HTTP Request Body
    request.httpBody = postString.data(using: String.Encoding.utf8)
     
    // Perform HTTP Request
    let session = URLSession.shared
    let task = session.dataTask(with: request, completionHandler: { (data, response, error) in
       
      guard let data = data else {
        return
      }

      do {
        let user = try JSONDecoder().decode([User].self, from: data)
         
         
      } catch {
        let str = String(decoding: data, as: UTF8.self)
        print(str)
         
      }
     
    })
    task.resume()
  }

here's the IBAction

   @IBAction func loggedInTapped(_ sender: Any) {
    // POST HTTP request
     
    goToUrl("http://13.228.251.27:8080/MobileAppTraining/AppTrainingLogin.htm")
    // transition to Profile Screen
      
  }

And struct of the User Object

  let idNumber: String
  let firstName: String
  let middleName: String?
  let lastName: String
  let emailAddress: String
  let mobileNumber: String
  let landline: String?
   
  static func loadUser() -> [User]? {
    return nil
  }
   
  static func loadSampleUsers() -> [User] {
    let user1 = User(idNumber: "", firstName: "", middleName: "", lastName: "", emailAddress: "", mobileNumber: "", landline: nil)
    return [user1]
  }
}

here's what I want

here's what I was getting