title: How to fix this error ' this class is not key value coding-compliant for the key containerView.'?
body: <p>When the user what to sign up or login it has error and get this error in the output "this class is not key value coding-compliant for the key containerView." 
  this is the login code also signup has the same error and l'm sure it's a right codes. </p>
  
  <pre><code>import UIKit
  import Firebase
  
  class LoginViewController: UIViewController {
  
    @IBOutlet var Aemeil: UITextField!
    @IBOutlet var Apassword: UITextField!
  
    override func viewDidLoad() {
        super.viewDidLoad()
    }
  
    @IBAction func login (_ sender : Any){
  
        guard let email = Aemeil.text, let password = Apassword.text
          else {
              print("Form is not valid")
              return
        }
  
        Auth.auth().signIn(withEmail: email , password: password , completion: { (user,error) in
          if error == nil{
              let vc = self.storyboard?.instantiateViewController(withIdentifier: "AHome");
              self.present(vc!, animated: true, completion: nil);
              print("Home page open")
          }
          else{
              let alertController = UIAlertController(title: "Error", message: error?.localizedDescription, preferredStyle: .alert)
              let defaultAction = UIAlertAction(title: "Yes", style: .cancel, handler: nil)
  
              alertController.addAction(defaultAction)
              self.present(alertController, animated: true, completion: nil)
          }         
  
      })
    }
  }
  </code></pre>