swift3 - Use of unresolved identifier 'emailTextField' in SignUpViewController.swift -

import uikit import firebaseauth import firebasedatabase  class signupviewcontroller: uiviewcontroller {      @iboutlet weak var usernametextfield: uitextfield!     @iboutlet weak var emailtextfield: uitextfield!     @iboutlet weak var passwordtextfield: uitextfield!      @iboutlet weak var profileimage: uiimageview!      var selectedimage: uiimage?      @ibaction func dismiss_onclick(_ sender: any) {         dismiss(animated: true, completion: nil)     }      override func viewdidload() {         super.viewdidload()          profileimage.layer.cornerradius = 60         profileimage.clipstobounds = true          let tapgesture = uitapgesturerecognizer(target: self, action: #selector(signupviewcontroller.handleselectprofileimageview))         profileimage.addgesturerecognizer(tapgesture)     }       func handleselectprofileimageview() {         print("tapped")     }        override func didreceivememorywarning() {         super.didreceivememorywarning()         // dispose of resources can recreated.     }      // [start create_user] }     func signupbtn_touchupinside(_ sender: any) {         auth.auth().createuser(withemail: emailtextfield.text!, password: passwordtextfield.text!, completion: { (user: user?, error: error?) in             if error != nil {                 print(error!.localizeddescription)                 return             }              var ref: databasereference!             ref = database.database().reference()             let usersreference = ref.child("users")             //   print(usersreference.description()) : https://customemaillogin-d64cf.firebaseio.com/             let uid = user?.uid             let newuserreference = usersreference.child(uid!)             newuserreference.setvalue(["username": self.usernametextfield.text!, "email": self.emailtextfield.text!])             print("description: \(newuserreference.description())")         })        }