is_home() function in Codeigniter

Question 1

You can use $this->router->fetch_class() to get the current controller and $this->router->fetch_method() to get the method too if needed.

So similar to the Yii example you linked to, you could do something like

$is_home = $this->router->fetch_class() === 'name_of_home_controller' ? true : false;

Or to match method too

$is_home = ($this->router->fetch_class() === 'name_of_home_controller' && $this->router->fetch_method() === 'name_of_home_method') ? true : false;

This way even if the page url is http://yoursite.com/ (assuming the home controller+method is the default), http://yoursite.com/home_controller/, http://yoursite.com/something/that/routes/to/home/controller/, etc, as long as it's calling that controller, it'll set $is_home to true.

Edit: Also you can use ($this->router->fetch_class() === $this->router->default_controller) if you don't want to explicitly state the home controller and it's set to the default controller.

Update for CI v3:
$this->router->fetch_class() and $this->router->fetch_method() were deprecated in CI v3. Use $this->router->class and $this->router->method instead.

Question 2

I just wanted to add my answer here as the other method doesn't work with my heavily modified version of CI.

This snippet is what I use to detect if we are on the homepage

if (!$this->uri->segment(1)) {
    // We are on the homepage
}

Question 3

if($this->uri->uri_string() == ''){ 
echo"You are on homepage"; 
}

Question 4

If you don't have a custom helper create one; otherwise inside any of your custom helper file just paste any of the following code snippets and you should be able to use is_home() from any location in Codeigniter.

function is_home()
{
   $CI =& get_instance();
   return (!$CI->uri->segment(1))? TRUE: FALSE;
}

OR

function is_home()
{
  $CI =& get_instance();
  return (strtolower($CI->router->fetch_class()) === $CI->router->default_controller  && $CI->router->fetch_method() === 'index') ? true : false;
}

Question 5

Why not just simply

public function name_of_home_method()
    {
        $data['is_home'] = true;
    }

Question 6

For better answer you should cover 2 routes for home page:

I assumes there is default controller like this in routes.php:

$route['default_controller'] = 'home';

Your home page without default controller name(like: yoursite.com)

Your home page with controller name(like: yoursite.com/home)

if(!$this->uri->segment(1) || $this->uri->segment(1)=='home'){ 
    // YOU ARE ON THE HOME
}