How to check if the user is logged in.

[eluser]Cinghius[/eluser]

Code:

if ($this->tank_auth->is_logged_in()) {         // logged in
$this->load->view("/shared/overlay",array(
'url' => site_url(),
'title' => 'LOGIN OK',
'text' => " Login ok!"
    
));
redirect('');

What I write on the home page after the redirect to check if the user is logged in, how do I make the control of that method?
I apologize if I have not explained well