2 Answers

• check out the kitchensink example

• A way is to use a converter xml2json like XMLtools.js from David Bankier. Htttp client retrieves you the xml and the lib converts to object.
  Here an example, how to use

  exports.getLatest = function(_callback) {
      require('offlinealert').create();
      var xhr = Ti.Network.createHTTPClient({
          timeout : 16000,
          onload : function() {
              var XMLTools = require('modules/XMLtools');
              var parser = new XMLTools(this.responseXML);
              var rss = parser.toObject();
              _callback((Object.prototype.toString.call(rss.channel.item) === '[object Array]' ) ? rss.channel.item : [rss.channel.item]);
          },
          onerror : function(e) {
              console.log(e.error);
          }
      });
      xhr.open('GET', 'http://www.podcampus.de/nodes.rss');
      xhr.send();
  }