Unknown Selector Issue - ios

Question

I am attempting to create a sign up page where people put such info as their email and desired password, after this is completed I want to switch to the next view controller however, I am getting the following error
[StudyBuddy.SignUpViewController signUpButton:]: unrecognized selector sent to instance 0x7fac5e061b80'
SignUpViewController
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)
}
})
}
}

Answer 1

You need to change your signupButton method declaration with signUpButton because inside your declaration u is lower latter for up you need to change it with Up because method name and property name are case sensitive or else change to selector with this signupButton one where you are adding target for button.