[StudyBuddy.SignUpViewController signUpButton:]: unrecognized selector sent to instance 0x7fac5e061b80'

import UIKit
import Firebase
import CoreData
import CoreLocation

class SignUpViewController: UIViewController {
    @IBOutlet weak var emailField: UITextField!
    @IBOutlet weak var passwordField: UITextField!
    @IBOutlet weak var confirmPasswordField: UITextField!

    override func viewDidLoad() {
        super.viewDidLoad()
        if let user = FIRAuth.auth()?.currentUser {



        }
        // Do any additional setup after loading the view.
    }

     override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }
    @IBAction func signupButton(sender: AnyObject)
    {
    if self.emailField.text == "" || self.passwordField.text == "" {

            let alertController = UIAlertController(title: "Oops!", message: "Please enter a valid username and password", preferredStyle: .Alert)
            let defaultAction = UIAlertAction(title: "Ok", style: .Cancel, handler: nil)
            self.presentViewController(alertController, animated: true, completion: nil)

        }

        else if self.confirmPasswordField.text != self.passwordField.text {

            let passwordAlert = UIAlertController(title: "Oops!", message: "Passwords do not match", preferredStyle: .Alert)
            let passwordAction = UIAlertAction(title: "Ok", style: .Cancel, handler: nil)

            self.presentViewController(passwordAlert, animated: true, completion: nil)
        }

        else {

            FIRAuth.auth()?.createUserWithEmail(emailField.text!, password: passwordField.text!, completion: {(user, error) in

                if error == nil {
                    self.performSegueWithIdentifier("goToSignUp", sender: sender)

                }
                else {
                    let createAlert = UIAlertController(title: "There was a problem", message: "There was a problem creating your account, please check the information you provided and try again", preferredStyle: .Alert)
                    let createAction = UIAlertAction(title: "Ok", style: .Cancel, handler: nil)
                    self.presentViewController(createAlert, animated: true, completion: nil)
                }

                })
        }


    }