Core Data Deletion Error

Question

Getting the following error when trying to delete a row from a tableview hooked to a fetched results controller:

* Assertion failure in -[UITableView _endCellAnimationsWithContext:], /SourceCache/UIKit_Sim/UIKit-1914.84/UITableView.m:1037 2012-07-12 13:11:19.921 Chef[28843:12203] * Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Invalid update: invalid number of rows in section 0. The number of rows contained in an existing section after the update (20) must be equal to the number of rows contained in that section before the update (20), plus or minus the number of rows inserted or deleted from that section (0 inserted, 1 deleted) and plus or minus the number of rows moved into or out of that section (0 moved in, 0 moved out).'

My code is below.

// Override to support editing the table view.
- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
if (editingStyle == UITableViewCellEditingStyleDelete) {

    // Delete the record from the DB
    RecipeCategory *objectToBeDeleted = [self.fetchedResultsController objectAtIndexPath:indexPath];
    [self.context deleteObject:objectToBeDeleted];

    // Delete the row from the data source
    [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];


}   
else if (editingStyle == UITableViewCellEditingStyleInsert) {
    // Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view
}   
}

Using a fetch request count, and the method - (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section, I have tried logging the number of DB records, and the number of rows in the table before and after the line [self.context deleteObject:objectToBeDeleted];, and they both decrease from 20 to 19.

Please help!

Edit: PS the error occurs at the deleteRowsAtIndexPath method.

Answer 1

It turns out that the line of code below was surplus to requirements. I guess the NSFetchedResultsController handles that as well. I also had to implement the delegate methods for NSFetchedResultsController.

// Delete the row from the data source
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];