wp_get_nav_menu_items( $menu )
retrieves all the menu item objects for a menu, but you have to specify the menu ID or menu name.
Here’s how to retrieve the menu items for the menu that is in a specific theme location (ex: primary).
$location = 'primary';
$theme_locations = get_nav_menu_locations();
if( empty( $theme_locations[ $location ] ) )
return;
$menu_items = wp_get_nav_menu_items( $theme_locations[ $location ] );