Best practices
Place the Share button in a convenient location, like a toolbar, to make it easy for people to start sharing or collaborating.
If necessary, customize the share sheet or sharing popover to offer the types of file sharing your app supports.
Write succinct phrases that summarize the sharing permissions you support.
Provide a set of simple sharing options that streamline collaboration setup.
Prominently display the Collaboration button as soon as collaboration starts.
Provide custom actions in the collaboration popover only if needed.
If it makes sense in your app, customize the title of the modal view’s collaboration-management button.
Consider posting collaboration event notifications in Messages.
For the complete guidance, including worked examples and illustrations, see the canonical page: https://developer.apple.com/design/human-interface-guidelines/collaboration-and-sharing