addUser.swift

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

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

  let task = URLSession.shared.dataTask(with: urlRequest) { (data, response, error) in
    guard error == nil else {
      print("error calling POST on \(addUserPath): \(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()
}