title: pushing UIDocumentIntractionController to UINavigationController
body: <p>I am working on app, which actually like Pdf reader. Here, I am using <code>UIDocumentIntractionController</code> to read documents. But when I am calling <code>[documentController presentPreviewAnimated:YES]</code> my naviagation bar Color becomes like transparent and dim. I think it is because of presenting <code>ViewController</code>. To avoid that I am searching some mechanism where I can push my document to navigation stack instead presenting my document it. Guide me with ideas.</p>
  
  <p>Thanks in advance.</p>