public function listComments($activityId, $fields = null, $max = 20, $order = null, $token = null, $alt = null)
	{
		if ($this->isAuthenticated())
		{
			$url = $this->getOption('api.url') . 'activities/' . $activityId . '/comments';

			// Check if fields is specified.
			if ($fields)
			{
				$url .= '?fields=' . $fields;
			}

			// Check if max is specified.
			if ($max != 20)
			{
				$url .= (strpos($url, '?') === false) ? '?maxResults=' : '&maxResults=';
				$url .= $max;
			}

			// Check if order is specified.
			if ($order)
			{
				$url .= (strpos($url, '?') === false) ? '?orderBy=' : '&orderBy=';
				$url .= $order;
			}

			// Check of token is specified.
			if ($token)
			{
				$url .= (strpos($url, '?') === false) ? '?pageToken=' : '&pageToken=';
				$url .= $token;
			}

			// Check if alt is specified.
			if ($alt)
			{
				$url .= (strpos($url, '?') === false) ? '?alt=' : '&alt=';
				$url .= $alt;
			}

			$jdata = $this->auth->query($url);

			return json_decode($jdata->body, true);
		}
		else
		{
			return false;
		}
	}