Filter – Apply sort for default next_post_link() and previous_post_link()
A sort will apply to all next / previous side-wide navigation links if the Next / Previous Apply option is turned on. In case this need to apply only when certain conditions are fulfilled .
The follogin filter can be used ‘apto/navigation_sort_apply’
add_filter('apto/navigation_sort_apply', 'theme_apto_navigation_sort_apply');
function theme_apto_navigation_sort_apply($current)
{
global $post;
if($post->post_type == 'post')
$current = TRUE;
else
$current = FALSE;
return $current;
}
The above will makes the code to apply the customized sort on navigation links only if post type is a Post.