Dynamically add items to a wp_nav_menu list

gistfile1.php

<?php


function bbg_activity_subnav( $items, $menu, $args ) {
	// Find the Activity item
	$bp_pages = bp_core_get_directory_page_ids();
	if ( isset( $bp_pages['activity'] ) ) {
		$activity_directory_page = $bp_pages['activity'];
	} else {
		return $items;
	}

	$activity_menu_item = 0;
	foreach ( $items as $item ) {
		if ( $activity_directory_page == $item->object_id ) {
			$activity_menu_item = $item->ID;
		}
	}

	if ( is_user_logged_in() ) {
		$new_items_data = array(
			array(
				'url' => trailingslashit( bp_loggedin_user_domain() . bp_get_activity_slug() ),
				'title' => 'Personal',
			),
			array(
				'url' => trailingslashit( bp_loggedin_user_domain() . bp_get_activity_slug() . '/' . bp_get_groups_slug() ),
				'title' => 'Groups',
			),
			array(
				'url' => trailingslashit( bp_get_root_domain() . '/' . bp_get_activity_root_slug() ),
				'title' => 'Sitewide',
			),
		);

		$menu_order = count( $items ) + 1;

		foreach ( $new_items_data as $new_item_data ) {
			$new_item = new stdClass;
			$new_item->menu_item_parent = $activity_menu_item;
			$new_item->url = $new_item_data['url'];
			$new_item->title = $new_item_data['title'];
			$new_item->menu_order = $menu_order;
			$items[] = $new_item;
			$menu_order++;
		}
	}

	return $items;
}
add_filter( 'wp_get_nav_menu_items', 'bbg_activity_subnav', 10, 3 );
?>