php通过HTTP_USER_AGENT判断是否为微信

/**
 * 判断是否是微信
 * @return number
 */
function is_ios8safari_wx()
{

    $ua = isset($_SERVER['HTTP_USER_AGENT']) ? strtolower($_SERVER['HTTP_USER_AGENT']) : '';
    if (stripos($ua, "baidubrowser")) {
        return 0;
    }
    if (stripos($ua, "iPhone") || stripos($ua, "iPad") || stripos($ua, "iPod") || stripos($ua, "iOS")) {
        if (stripos($ua, 'MicroMessenger') || stripos($ua, '(KHTML, like Gecko) Version/8.0 Mobile') || stripos($ua, '(KHTML, like Gecko) Version/9.0 Mobile')) {
            return 1;
        }
    }
    return 0;
}