使用页面id获取自定义导航标题：

function get_custom_nav_title( $menu_name, $page_id ) { 
    $args = array(
        \'order\'                  => \'ASC\',
        \'orderby\'                => \'menu_order\',
        \'post_type\'              => \'nav_menu_item\',
        \'post_status\'            => \'publish\',
        \'output\'                 => ARRAY_A,
        \'output_key\'             => \'menu_order\',
        \'nopaging\'               => true,
        \'update_post_term_cache\' => false 
    );
    $items = wp_get_nav_menu_items( $menu_name, $args );
    //print_r( $items );
    foreach ( $items as $item ) {
        if ( $item->object_id == $page_id ) {
            return $item->title;
        }
    }   
}