specify file types with your app

filetypes

/*
This goes in your Info.plist
it's been a while since I added this functionality so I'm not sure what was added and what was already there, you may already have some pieces of the code. 

When you tap and hold a mail attachment your app will show up in the list of associated apps and switch to your app when selected.
*/

<key>CFBundleURLTypes</key>
<array>
  <dict>
    <key>CFBundleURLName</key>
    <string>YOUR APPLICATION ID</string>
    <key>CFBundleURLSchemes</key>
    <array>
      <string>YOUR APP NAME</string>
    </array>
  </dict>
</array>
<key>CFBundleDocumentTypes</key>
<array>
  <dict>
    <key>CFBundleTypeIconFiles</key>
    <array>
      <string>YOUR ICON FILES</string>
      <string>YOUR ICON FILES</string>
    </array>
    <key>CFBundleTypeName</key>
    <string>Songwriter Files</string>
    <key>CFBundleTypeRole</key>
    <string>Viewer</string>
    <key>LSHandlerRank</key>
    <string>Owner</string>
    <key>LSItemContentTypes</key>
    <array>
      <string>public.plain-text</string>
      <string>com.microsoft.waveform-audio</string>
      <string>org.gnu.gnu-zip-archive</string>
    </array>
  </dict>
</array>
<key>CFBundleIdentifier</key>
<string>YOUR APPLICATION ID</string>