title: How to ensure that my app never comes up as the default for "Open In..."
body: <p>My iPhone app registers itself as an "Alternate" handler for PDF files in CFBundleDocumentTypes, and recently I've started to get complaints from users about the fact that it has displaced iBooks as the default "Open In..." app for PDFs; it seems that iBooks only registers itself as an "Alternate" handler for PDFs too, and that the system is defaulting to my app instead of to iBooks.</p>
  
  <p>Is there any way I can tell iOS that under no circumstances should it make my app the default "Open In..." if there's any other app on the system that can handle this file type?</p>