How to register app to receive screenshots taken by other apps directly

Question

My app can already receive PDFs, PNG, JPGs from other apps via CFBundleDocumetTypes - Definitions. This means, once you chose the share-Button of other apps, my app appears in the list. So far so good. Opening a saved screenshot on an iPad also presents a symbol of my app to put it to.

But if I take a screenshot and want to send it directly, my app does not appear as possible receiver. I first have to save it somewhere first. How can I tell iOS to show my app as receiver for just-made-screenshots, just out of the editing view of the screenshot-feature?

When I send it as mail-attachment, it shows up as a .jpeg. Here is an exempt of my info.plist:

    <key>CFBundleDocumentTypes</key>
<array>
    <dict>
        <key>CFBundleTypeName</key>
        <string>PDF</string>
        <key>LSHandlerRank</key>
        <string>Alternate</string>
        <key>LSItemContentTypes</key>
        <array>
            <string>com.adobe.pdf</string>
        </array>
    </dict>
    <dict>
        <key>CFBundleTypeName</key>
        <string>PNG</string>
        <key>LSHandlerRank</key>
        <string>Alternate</string>
        <key>LSItemContentTypes</key>
        <array>
            <string>public.png</string>
        </array>
    </dict>
    <dict>
        <key>CFBundleTypeName</key>
        <string>JPG</string>
        <key>LSHandlerRank</key>
        <string>Alternate</string>
        <key>LSItemContentTypes</key>
        <array>
            <string>public.jpeg</string>
            <string>public.jpg</string>
        </array>
    </dict>
</array>