title: Cannot use Firebase authentication: FIRAuth.auth does not work
body: <p>I have been struggling with this issue for a few days, I am a rookie and I am not able to find a solution. I am trying to create a user sign up and log in page using XCode 8.3.3 and am using Firebase as database.</p>
  
  <p>My code is as follows:</p>
  
  <pre><code>import UIKit
  import Firebase
  import FirebaseAuth
  
  class SignUpViewController: UIViewController {
  
      //Outlets
      @IBOutlet weak var emailTextField: UITextField!
      @IBOutlet weak var passwordTextField: UITextField!
  
      //Sign Up Action for email
      @IBAction func createAccountAction(_ sender: AnyObject) {
  
          if emailTextField.text == "" {
              let alertController = UIAlertController(title: "Error", message: "Please enter your email and password", preferredStyle: .alert)
  
              let defaultAction = UIAlertAction(title: "OK", style: .cancel, handler: nil)
              alertController.addAction(defaultAction)
  
              present(alertController, animated: true, completion: nil)   
          } else {
              FIRAuth.auth().createUser(withEmail: emailTextField.text!, password: passwordTextField.text!) { (user, error) in
  
              if error == nil {
                  print("You have successfully signed up")
                  //Goes to the Setup page which lets the user take a photo for their profile picture and also chose a username
  
                  let vc = self.storyboard?.instantiateViewController(withIdentifier: "Home")
                  self.present(vc!, animated: true, completion: nil)
  
              } else {
                  let alertController = UIAlertController(title: "Error", message: error?.localizedDescription, preferredStyle: .alert)
  
                  let defaultAction = UIAlertAction(title: "OK", style: .cancel, handler: nil)
                  alertController.addAction(defaultAction)
  
                  self.present(alertController, animated: true, completion: nil) 
              }
          }
      }   
  }
  </code></pre>
  
  <p>The part that has issue is <code>FIRAuth.auth</code>. The error says "<code>FIRAuth</code> has been renamed to Auth" and if I applied such fix, although the built became successful, I could only see nothing but a white screen. If I delete the code then I can see a normal sign in screen created earlier.</p>
  
  <p>Another thing is when I type import <code>FirebaseAuth</code> a red line appeared in the suggested word list that crossed out <code>FirebaseAuth</code>, I still proceeded.</p>
  
  <p>Please help. I don't know why it happens. Could there be any missing pod files? Much appreciated.</p>
  
  <p>Storyboard:
  <a href="https://i.stack.imgur.com/KwOXK.png" rel="nofollow noreferrer">storyboard</a></p>