I am a beginner. I am developing an app with swift. I am using Firebase for signin. But I was wondering if I need to write codes to check user's sign-in status for each viewController for security. Or sign-in is needed only for the sign-in viewController like locking just a front door. My code may not be needed but below is the code that I wrote:

```
        // Mark: User Sign-in Status Recheck
        Auth.auth().addStateDidChangeListener { auth, user in
            if user != nil {
                if let user = user {
                    let userUid = user.uid
                    let userEmail = user.email
                }
            } else {
                let InitialSignInFirstViewController = self.storyboard?.instantiateViewController(withIdentifier: "SignInFirstViewController") as! InitialSignInViewController
                self.present(SignInFirstViewController, animated: false, completion: nil)
            }
        }

```