MyApp.swift

@IBAction func signUpButtonTapped(sender: AnyObject)
    {        
        let username = usernameTextField.text
        let email = emailTextField.text
        let password = passwordTextField.text
        
        if username != "" && email != "" && password != "" {
            DataService.dataService.BASE_REF.createUser(email, password: password, withValueCompletionBlock: { error, result in
                if error != nil {3
                    self.signupErrorAlert("Oops!", message: "Having some trouble creating your account. Please try again.")
                    print(error)
                } else {
                    DataService.dataService.BASE_REF.authUser(email, password: password, withCompletionBlock: { err, authData in
                        let user = ["provider": authData.provider!, "email": email!, "username": username!]
                        DataService.dataService.createNewAccount(authData.uid, user: user)
                    })
                    NSUserDefaults.standardUserDefaults().setValue(result ["uid"], forKey: "uid")
                    self.performSegueWithIdentifier("NewUserLoggedIn", sender: nil)
                }
            })
        } else {
            signupErrorAlert("Oops!", message: "Don't forget to enter your email, password, and a username.")
        }
    }