I'm wading through the documentation and finding lots of different things about inter-app communication and sending files around and starting apps from other apps, but I haven't found any screenshots or sample results in the documentation. I'm getting overwhelmed and I just want to know what is actually being used to accomplish the thing in the following screenshot:
Once you click one of the app options in that overlay, another screen opens that contains the text from the Note file, and it is a different screen depending on your choice. If you click Messages, it prepares to send a text. If you click Messenger it prepares to send a message, etc.
It SEEMS like this is just about registering a corresponding file type, but I'm not sure what file type a Notes file really is or if that is what is actually going on at this point. To be clear, I'm asking: what is it that Messages, Mail, Slack, and Messenger do in their apps to make them appear in that list and respond when they are chosen?
EDIT: I've added this to my plist file but I still don't see it appearing from the Notes app:
<key>CFBundleDocumentTypes</key>
<array>
<dict>
<key>CFBundleTypeName</key>
<string>text</string>
<key>LSHandlerRank</key>
<string>Alternate</string>
<key>LSItemContentTypes</key>
<array>
<string>public.plain-text</string>
<string>public.text</string>
<string>public.utf8-plain-text</string>
<string>public.utf16-external-plain-text</string>
<string>public.utf16-plain-text</string>
<string>com.apple.traditional-mac-plain-text</string>
</array>
</dict>
</array>