src/IronMQ.php
public function reserveMessage($queue_name, $timeout = self::GET_MESSAGE_TIMEOUT, $wait = self::GET_MESSAGE_WAIT)
    {
        $messages = $this->reserveMessages($queue_name, 1, $timeout, $wait);
        if ($messages) {
            return $messages[0];
        } else {
            return null;
        }
    }
public function reserveMessage($queue_name, $timeout = self::GET_MESSAGE_TIMEOUT, $wait = self::GET_MESSAGE_WAIT)
    {
        $messages = $this->reserveMessages($queue_name, 1, $timeout, $wait);
        if ($messages) {
            return $messages[0];
        } else {
            return null;
        }
    }
Reserve single message from queue

@param string $queue_name Queue name
@param int $timeout
@return mixed|null single message or null