add catogries to post type

//enable catogries and tags for pages
function myplugin_settings() {
    // Add tag metabox to page
    register_taxonomy_for_object_type('post_tag', 'page');
    // Add category metabox to page
    register_taxonomy_for_object_type('category', 'page');
}
 // Add to the admin_init hook of your theme functions.php file
add_action( 'init', 'myplugin_settings' );