I fixed a typo in my Info.plist entry and now it works. Here is the actual entry I used...
<key>MSSupportedPresentationContexts</key>
<array>
<string>MSMessagesAppPresentationContextMessages</string>
<string>MSMessagesAppPresentationContextMedia</string>
</array>
Now my extension appears in the Sticker context and is available in other apps.
Topic:
App & System Services
SubTopic:
General
Tags: