Check if User is Logged In Codeigniter

step 1 :- Step created this code
For Example
<?php
class Admin extends MY_Controller
{
public function dashboard()
{
$this->load->model(‘articlesmodel’,’articles’);
$articles=$this->articles->articles_list();
$this->load->view(‘admin/dashboard’,[‘articles’=>$articles]);
}
public function add_article()
{

}
public function edit_article()
{

}
public function delete_article()
{

}
public function __construct()
{
parent::__construct();
if(! $this->session->userdata(‘user_id’))
return redirect(‘login’);
}
}
?>