example/Server.php
protected function getIfModifiedSinceHeader()
    {
        $modifiedSince = null;

        if (isset($_SERVER['HTTP_IF_MODIFIED_SINCE'])) {
            $modifiedSince = $_SERVER['HTTP_IF_MODIFIED_SINCE'];

            if (false !== ($semicolonPos = strpos($modifiedSince, ';'))) {
                $modifiedSince = substr($modifiedSince, 0, $semicolonPos);
            }
        }

        return $modifiedSince;
    }
protected function getIfModifiedSinceHeader()
    {
        $modifiedSince = null;

        if (isset($_SERVER['HTTP_IF_MODIFIED_SINCE'])) {
            $modifiedSince = $_SERVER['HTTP_IF_MODIFIED_SINCE'];

            if (false !== ($semicolonPos = strpos($modifiedSince, ';'))) {
                $modifiedSince = substr($modifiedSince, 0, $semicolonPos);
            }
        }

        return $modifiedSince;
    }
protected function getIfModifiedSinceHeader ( ) { $ modifiedSince = null ; if ( isset ( $ _SERVER [ 'HTTP_IF_MODIFIED_SINCE' ] ) ) { $ modifiedSince = $ _SERVER [ 'HTTP_IF_MODIFIED_SINCE' ] ; if ( false !== ( $ semicolonPos = strpos ( $ modifiedSince , ';' ) ) ) { $ modifiedSince = substr ( $ modifiedSince , 0 , $ semicolonPos ) ; } } return $ modifiedSince ; }
Get If-Modified-Since header from client request

@return string|null
Get If - Modified - Since header from client request