Controller snippet

//constructor
public PubHomeController() {
        pub = [SELECT id FROM Network WHERE Name LIKE '%Power of Us%'];
}

public class Topic {
        public String createdDate { get; private set; }
        public String id { get; private set; }
        public String description { get; private set; }
        public Integer talkingAbout { get; private set; }
        public String name { get; private set; }
    }
    
    public class TopicResponse {
        public list<Topic> topics;
    }
    
    public list<Topic> getTrendingTopics(){
        try {
            //we'll call the REST API here
            http h = new http();
     
            httprequest req = new httprequest();
            req.setEndpoint(baseEndpoint + '/services/data/v28.0/connect/communities/' + pub.id + '/chatter/topics?pageSize=5');
            req.setMethod('GET');
            req.setHeader('Authorization', 'OAuth ' + session);
            req.setTimeout(60000);
     
            httpresponse res = h.send(req);
            system.debug('TopicsResponseBody:' + res);       
            TopicResponse tr = (TopicResponse)JSON.deserialize(res.getBody(), TopicResponse.class);
            return tr.topics;
        } catch (Exception e) {
          return null;
        }

    }

Page

<h4>Popular Topics</h4>
                                    
<ul style="list-style-type: none;margin-left:0px;">
    <apex:repeat value="{!TrendingTopics}" var="topic" >
      <li><a href="/_ui/core/chatter/topics/TopicPage?id={!topic.id}" class="viewPopularTopic">#{!topic.name}</a></li>
    </apex:repeat>
                                        

</ul>