How to make user object available across pages in CodeIgniter?

I'm fairly new to CodeIgniter and I'm using Ion Auth for user authorization. With the Ion Auth library, you get a user object like:

  $user = $this->ion_auth->get_user();
  echo $user->email;

If a user is logged in, I want the $user object to be available on any of the pages (in any of the controllers). How can I do this? (I'm using CodeIgniter 2)

This blog post of mine goes into a lot of detail in specifically using Ion_Auth to allow your entire application (including views) to access your current user's information.

The short version... (specifically for the topic at hand)

Adding this to your MY_Controller.php file

class User_Controller extends CI_Controller {

    protected $the_user;

    public function __construct() {

        parent::__construct();

        if($this->ion_auth->logged_in()) {
            $data->the_user = $this->ion_auth->get_user();
            $this->the_user = $data->the_user;
            $this->load->vars($data);
        }
        else {
            redirect('/');
        }
    }
}

Then in your application just create your controller like this

class App_Controller extends User_Controller {

    public function __construct() {
        parent::__construct();
    }

    function index() {
        //do stuff
    }
}

Then not only in your controller will you have access to $this->the_user but you will also have $the_user loaded into every view with $this->load->vars()