Hiding/Disabling Sign up Button on Login after Successful Sign up

Hi!

I am using Firebase and want to disable the sign up button to personalise experience for signed up users on the login view. I am using below but it doesn't seem to work. Anyone knows what I should change?

extension LoginViewController: AuthUIDelegate {
func handleAuthenticated(_ Button: UIButton) -> Bool { if Auth.auth().currentUser != nil {      createAccountButton.isHidden = true     } else {       createAccountButton.isHidden = false     }   return true   } }