title: RestKit: Map single object into existing array
body: <p>I have the following JSON structure which i get from a RestService:</p>
  
  <pre><code>{
      "customer": {
          "id": "123456",
          [more attributes ....]
          "items": [
              {
                  "id": "1234",
              },
              {
                  "id": "2345",
              }
              [more items...]
          ]
      }
  }
  </code></pre>
  
  <p>which i successfully map into Core Data using RestKit. From another RestService (which i can not change) i then get more details to one single item in the items array. the JSON answer looks like</p>
  
  <pre><code>{
      "customer": {
          "id: "123456",
          "item": {
              "id": "1234",
              "name": "foo",
              [other attributes...]
          }
      }
  }
  </code></pre>
  
  <p>Now the question: How can i map the second answer, so that the single item is added to the items array (or updated if it is already in there)?</p>
  
  <p>Thanks for any ideas!</p>