The documentation for beginUpdates() and endUpdates() state to “Use the performBatchUpdates(_:completion:) method instead of this one whenever possible.” So I thought it would be better to go with alternate implementation of NSFetchedResultsControllerDelegate that does not implement controllerWillChangeContent(_:) and controllerDidChangeContent(_:), and instead calls performBatchUpdates(_:completion:) in controller(_:didChange:at:for:newIndexPath:) and controller(_:didChange:atSectionIndex:for:). Turns out, that results in an invalid number of rows exception when adding a new section. Since I can’t delete this post, I thought I’d at least provide an explanation in case anyone else had this idea. ¯\_(ツ)_/¯