controller

<?php
class Login extends CI_Controller{
    public function index(){
        $this->load->model('User_model');
        $model = $this->User_model;

        if(isset($_POST['btnSubmit'])){
            $model->username = $_POST['username'];
            $model->password = $_POST['password'];


            if ($model->authenticate()){
                $this->load->view('login_success_view');
            }else{
                $this->load->view('login_eror_view');
            }
        }else{
            $this->load->view('login_form_view', array('model'=>$model));
        }
    }
}