lib/AmazonSNS.php
public function listTopics($nextToken = null) {
		$params = array();

		if(!is_null($nextToken)) {
			$params['NextToken'] = $nextToken;
		}

		$resultXml = $this->_request('ListTopics', $params);

		// Get Topics
		$topics = $resultXml->ListTopicsResult->Topics->member;

		return $this->_processXmlToArray($topics);
	}
public function listTopics($nextToken = null) {
		$params = array();

		if(!is_null($nextToken)) {
			$params['NextToken'] = $nextToken;
		}

		$resultXml = $this->_request('ListTopics', $params);

		// Get Topics
		$topics = $resultXml->ListTopicsResult->Topics->member;

		return $this->_processXmlToArray($topics);
	}
List SNS topics

@link http://docs.amazonwebservices.com/sns/latest/api/API_ListTopics.html
@param string|null $nextToken [optional] Token to retrieve next page of results
@return array