How to Add a Sub Menu Page to a Custom Post Type?

Question

I am trying to create a link under a custom post type I have named "portfolios". If I change "add_submenu_page" to "add_options_page" it correctly shows a new link under the "Settings" menu. But it won't seem to go in the portfolios menu, what am I doing wrong here?

    add_action('admin_menu', 'mt_add_pages');


    function mt_add_pages() {
    add_submenu_page(__('portfolios','menu-test'), __('Test Settings','menu-test'), 'manage_options', 'testsettings', 'mt_settings_page');


    function mt_settings_page() {
    echo "<h2>" . __( 'Test Settings', 'menu-test' ) . "</h2>"; 

    }

    }

Answer 1

It looks like you are looking for labels for custom post types. You can get an example on this website: http://teamtreehouse.com/blog/create-your-first-wordpress-custom-post-type

Answer 2

add_options_page automatically adds it underneath settings, however add_submenu_page gives you control as to where you want it to show up.

Try something like this:

add_submenu_page('edit.php?post_type=portfolios', __('Test Settings','menu-test'), 'manage_options', 'testsettings', 'mt_settings_page');

Documentation: https://codex.wordpress.org/Function_Reference/add_submenu_page