Is there a difference between the method of helper and library are called upon in code igniter?

Question

I am getting little bit confused, the way the methods of library and helper are used in code igniter. I am still learning code igniter.

CONTROLLER

function index(){
    $this->load->helper('text');
    $this->load->library('auth'); //custom library

    $data['string'] = 'this is sample ..... this is sample';
    $this->load->view('article', $data);
}

VIEW

<?php 
if(is_logged_in()){    //is_logged_in() is the method from the library, 'auth'
    echo 'You are logged in';
}
<p><?php echo word_limiter($string, 10); ?></p> <!--word_limiter() is the method from the helper, 'text' -->

In the above view file, the helper method word_limiter() works fine. But the method is_logged_in() does not work. But if I do ($this->auth->is_logged_in()), it will work.

But why the method from helper i.e. word_limiter() does not have to be written like this ($this->text->word_limiter()).

Is there a difference between the method of helper and library are called upon ?

Answer 1

A CodeIgniter helper is a set of related functions (Common functions) which you could use them within Models, Views, Controllers,.. everywhere.

Once you load (include) that file, you can get access to the functions.

But a Library is a class, which you need to make an instance of the class (by $this->load->library()). And you'll need to use the object $this->... to call the methods.

As a thumb rule: A library is used in object oriented context (Controller, ...), while a helper is more suitable to be used within the Views (non object oriented).