Small mu-plugin that adds a cookie to requests when the mobile theme is being shown. Used for caching scenarios.

wptouch-add-cookie-to-request.php

<?php
/**
 * Plugin Name: WPtouch add cookie and request no caching to mobile requests.
 * Version: 0.1
 * Description: Adds cookies to session when mobile theme is showing as well as sets cache-control headers.
 * Author: Zach Wills <zach@wptouch.com>
 * Author URI: https://www.wptouch.com/
 * Text Domain: wptouch-pro
 * Domain Path: languages
 * License: GPL
 */

function send_wptouch_cookie_if_mobile_theme_showing() {
	setcookie( 'wptouch_mobile_theme_showing', true, 0 );
}
add_action( 'wptouch_mobile_theme_showing', 'send_wptouch_cookie_if_mobile_theme_showing' );

function request_no_caching_when_mobile_theme_showing() {
	$ts = gmdate("D, d M Y H:i:s") . " GMT";
	header("Expires: $ts");
	header("Last-Modified: $ts");
	header("Pragma: no-cache");
	header("Cache-Control: no-cache, must-revalidate, maxage=0");
}
add_action( 'wptouch_mobile_theme_showing', 'request_no_caching_when_mobile_theme_showing' );