title: Present preview from UIDocumentInteractionControlller as ChildViewController of a UIViewController
body: <p>I have implemented UIDocumentInteractionController for previewing unsupported filetypes. But since UIDocumentInteractionController is subclass of NSObject and not UIViewController, I am not able to add it as childviewcontroller of present onscreen UIViewController, as its view property is not exposed.</p>
  
  <p>I can only present it as modal or over navigation stack and not as inline UIView subview.</p>
  
  <p>Tried QLPreviewController but it doesn't support file icons and other useful exposed methods as exposed in UIDocumentInteractionController</p>