How to check if a library exist in a controller?

Check if object is available:

PHP Code:

$is_loaded = is_object(@$this->upload) ? TRUE : FALSE;// @ sign suppressed error if object didn't exist
var_dump($is_loaded);
exit; 


Now you just need to make your own method that take a parameter as name of library:

PHP Code:

private function is_lib($lib)
{
    return is_object(@$this->{$lib}) ? TRUE : FALSE;
} 


PHP is_object function.