passing function to the view in CodeIgniter?

Can I pass a function to the view in CodeIgniter? The function basically checks if the session value is set. For example:

public function is_logged(){
    $logged = $t开发者_如何学JAVAhis->session->userdata('user_id');

    if ($logged){
        return true;
    } else {
        redirect('index');
    }
}

Now i want to place this function on some of my view. so how can i pass this function to the view? Thanks.

I would take a different approach, much like @atno said: you're using MVC pattern, so doing this kind of checks in your view is 'logically' wrong as well as going against a DRY approach.

I would do the check in controller, using the function I have in the model, and load the appropriate view according to the results:

class Mycontroller extends CI_Controller {

     function index() //just an example
     {
        $this->load->model('mymodel');  
        if($this->mymodel->is_logged())
        {
          $this->load->view('ok_page');
        }
        else
        {
          $this->load->view('not_logged_view');
          //OR redirect('another_page','refresh')
        }
    }
}

In your model:

 function is_logged()
 {
    $logged = $this->session->userdata('user_id');

    if ($logged)
    {
        return TRUE;
    } else {
        return FALSE;
    }
 }

If it's someting you need to do programmatically, for every method of a controller (like checking for being logged in), you can check inside the constructor:

  function __construct()
  {
    parent::__construct();
    // check code here
  }

In this way you'll have the check before any method of the controller is called, i.e. upon controllers' initialization.

UPDATE: using a model can be overkill here, you can just check what $this->session returns:

function index() { // or mypage() or whatever

if($this->session->user_data('user_id'))
{
  $this->load->view('ok_page');
}
else
{
  $this->load->view('not_ok_page');
}

}

You shouldn't be doing that. Just have this code directly in your layout, or just have it in your view.

You could also create a helper : http://codeigniter.com/user_guide/general/helpers.html