updateUser.swift

static func updateUser(id: Double, name: String, completionHandler: @escaping (_ userID: Double?, _ error: Error?) -> Void) {
  let endpointUrl = URL(string: host + updateUserPath)!
  var urlRequest = URLRequest(url:  endpointUrl)
  urlRequest.httpMethod = "PUT"

  let userDict: [String: Any] = ["id": id, "name": name]
  let userData = try! JSONSerialization.data(withJSONObject: userDict, options: [])
  urlRequest.httpBody = userData

  let task = URLSession.shared.dataTask(with: urlRequest) { (data, response, error) in
    guard error == nil else {
      print("error calling PUT on \(updateUserPath): \(error!)")
      DispatchQueue.main.async {
        completionHandler(nil, error)
      }
      return
    }

    let userData = try! JSONSerialization.jsonObject(with: data!, options: []) as! [String: Double]
    let userID = userData["id"]
    DispatchQueue.main.async {
      completionHandler(userID, nil)
    }
  }
  task.resume()
}