(swift) do not let anonymous users in - swift

Question

my app needs from the user to log in. okay i connected my app to parse, and in the login view controller i wrote these codes
import UIKit
class SigninPageViewController: UIViewController {
#IBOutlet weak var userNameTextField: UITextField!
#IBOutlet weak var userEmailTextField: UITextField!
#IBOutlet weak var userPasswordTextField: UITextField!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view.
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
#IBAction func doneButtonTapped(sender: AnyObject) {
let userEmail = userEmailTextField.text;
let userPassword = userPasswordTextField.text;
PFUser.logInWithUsernameInBackground(userEmail, password: userPassword) {
(user: PFUser?, error: NSError?) -> Void in
if user != nil {
// Login is successful
NSUserDefaults.standardUserDefaults().setBool(true, forKey:"isUserLoggedIn");
NSUserDefaults.standardUserDefaults().synchronize();
self.dismissViewControllerAnimated(true, completion: nil);
} else {
println("Could not find user")
}
}
}
}
the problem is when i tried my app and tried to write the wrong email and the wrong password, the app let me log in without checking if the user is exist or not and without printing line (Could not find user). So the question here is how to let my app check if the user is exist or not, and do not let anonymous users in.

Answer 1

You could establish your own requirements for logging in. If you do a fetch for the user with the email address they entered, you can allow log in only if the email address exists. If it doesn't, just send the user an alert, and don't go through with the login.