User Auth Library

[eluser]Unknown[/eluser]
I just want to write a helper function that checks if you are logged in, and if not it will redirect you to the login page. It seems that I cannot access $this->session through a helper function though.

Basic function:

Code:

function check_logged_in()
{
    $logged_in = $this->session->userdata('logged_in');
    //$client_id = $this->session->userdata('client_id');

    if (!$logged_in)
    {
        redirect('/login');
    }
}

If I try to call that function via the helper then I get a server error 500. However, if I put that same code into the a controller function then it works just fine.

Would I need to use a hook in this case?