title: How do I register a custom filetype in iOS
body: <p>I am currently creating a app in which i want to let the user backup their files (plist + m4a). I zip the files and change the extension to a custom one (specifically for my app, say "*.MyBackup"). The user can then either export via email or with iTunes file sharing.</p>
  
  <p>I have already read about CFBundleDocumentTypes but didn't really get what I had to do with them.</p>
  
  <p>The part where i am currently stuck at is how to associate my extension with my app. If the user sends himself an email with the "custom"-zip file he's supposed to be able to open it with my app.</p>
  
  <p>How do I do this and what are "UTExportedTypeDeclarations"?</p>