UITableView internal bug: unable to generate a new section map with old section count: and new section count: with userInfo (null)

Question

I haven't seen this error before, and I did a search as to why it may be happening but couldn't find any info on it:

CoreData: error: Serious application error. An exception was caught from the delegate of NSFetchedResultsController during a call to -controllerDidChangeContent:. UITableView internal bug: unable to generate a new section map with old section count: 1 and new section count: 0 with userInfo (null)

Does anyone know what might be happening here? I am not sure about the "internal bug" part - does this error indicate a problem with my code or a bug in UITableView?

Answer 1

Stephan already mentioned this in a comment on the original question but I thought it was worth sharing some code. This answer was actually sourced from a comment made by user GERUB on a thread on the apple dev forums found here: https://forums.developer.apple.com/thread/9964

if tableView.numberOfRowsInSection(indexPath.section) == 1{  
    tableView.deleteSections(NSIndexSet(index: indexPath.section), withRowAnimation: .Automatic)  
}else{  
    tableView.deleteRowsAtIndexPaths([indexPath], withRowAnimation: .Automatic)  
} 

I have tested this inside of the NSFetchedResultsControllerDelegate method implementations and it works perfectly.

Answer 2

Did you use this NSFetchedResultsController in multiple UITableView. If so, that's the cause. Use one NSFetchedResultsController for one UITableView. Do not just switch queries when switching views.