How to keep offset when scrolling to top?

My datasource load new items from server, and when method "loadPrevious()" add new items, chat automatically scroll to the top, don't keeps offset at previously shows message.

Start by locating the implementation and callers of loadPrevious() in the Swift chat framework, then reproduce loading older messages while scrolled away from the top. Done means newly inserted items preserve the previously visible message offset instead of jumping to the top; add or update the relevant regression test if the existing test structure identifies one.

Written by the indexing model from the issue text.