UIActivityViewController has an undocumented property introduced in iOS/iPadOS/Mac Catalyst 15.4 called allowsProminentActivity.
What does it do?
What does UIActivityViewController's `allowsProminentActivity` property do?
Effectively, doc is totally empty (not the first time so).
There is another property: var excludedActivityTypes: [UIActivity.ActivityType]?
So, would allowsProminentActivity enable activities considered as most usual (prominent) ?
In anycase, that's worth a bug report against documentation as 15.4 is now released, not a beta.
It's related to SharePlay. See What's new in SharePlay from WWDC22.
tl;dw when allowsProminentActivity is true the green Share Play button is shown at the top of the sheet, when false it's shown down below with the other actions.