iOS Share Activity - Add Custom Actions

See the image attached.

What are the APIs needed to add an action here that shows up across the system.

Not a share extension, but the list of actions that are below that.

How did Pinterest add theirs here? And it shows up for almost everything you share.

I've been looking around and the only thing that looked like maybe is UIActivity. But when I implemented it doesn't show up across other apps.

I was also lookin through app shortcut and app intent documentation but I can't find exactly how Pinterest is providing this action here.

Are they not just "shortcuts"

iOS Share Activity - Add Custom Actions
 
 
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