Detecting a users first visit to a website using codeigniters session library

[eluser]Clooner[/eluser]
I use something like this.

Code:

function isNew()
{
    $CI = & get_instance();
    $this->_key = $CI->session->userdata('visitor_key');
    if (!$this->_key)
    {
        $this->_key = uniqid();
        $CI->session->set_userdata('visitor_key', $this->_key);
        return true;
    }
    return false;
}

You will need to load the session library and make sure your settings are correct. I have this in a library but you could put it also in a (MY_)Controller with minor adjustments!