Here what i try @IBAction func userButtonTapped(_ sender: UIButton) {

let userEmail = userEmailTextField.text! as String
let userPassword = userPasswordTextField.text! as String

let parameters = ["auth": ["password": userPassword, "email": userEmail] ]

let urlString = "http://localhost:3000/user_token"


Alamofire.request(urlString, method: .post, parameters: parameters, encoding: JSONEncoding.default, headers: [:])
.responseString { response in
print("Success: \(response.result.isSuccess)")
print("Response String: \(response.result.value)")
if let httpError = response.result.error {
_ = httpError.localizedDescription
// show the error message to user

} else { //no errors
if response.result.value == userEmail {
print("Email is invalid/(email)")
} else {
print("Success: \(response.result.isSuccess)")
print("Response String: \(response.result.value)")
let defaults = UserDefaults.standard
defaults.set(true, forKey: "isUserLoggedIn")
defaults.synchronize()

self.dismiss(animated: true, completion: nil)
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let tabBarController = storyboard.instantiateViewController(withIdentifier: "tabBarController") as! UITabBarController
let appDelelegate = UIApplication.shared.delegate as! AppDelegate
appDelelegate.window?.rootViewController = tabBarController
}
}
}

что в ответе приходит?