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I have a fetched result with a single section. I am able to access the objects using [[fetchedResultsController fetchedObjects] objectAtIndex:index] for all of the objects. But it is failing when I use objectAtIndexPath like this: [fetchedResultsController objectAtIndexpath:indexPath]

An error occurs after I insert an row (for one of the SearchResult objects) into the corresponding table. The object appears to be inserted into the new table correctly. After I have visually confirmed this, I select one of the rows, and then the fun begins.

Here is the code where the error is occurring:

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    SearchResult *event;
    NSLog(@"Number of sections in fetchedResultsController: %d", [[fetchedResultsController sections] count]);
    for (NSUInteger i=0; i<[[fetchedResultsController fetchedObjects] count]; i++) {
        event = (SearchResult*)[[fetchedResultsController fetchedObjects] objectAtIndex:i];
        NSLog(@"object at index[%d]: %@", i, event.title );
        NSLog(@"indexPath for object at index[%d]:%@", i, [fetchedResultsController indexPathForObject:event]);
    }

    NSLog(@"indexPath passed to method: %@", indexPath);

    SearchResult *result = [fetchedResultsController objectAtIndexPath:indexPath];  // *** here is where the error occurs ***

    [viewDelegate getDetails:result];
}

I am having a failure in the last line. The log looks like this:

Number of sections in fetchedResultsController: 1
object at index[0]: Cirles
indexPath for object at index[0]:(null)
object at index[1]: Begin
indexPath for object at index[1]:(null)
object at index[2]: Copy
indexPath for object at index[2]:(null)
object at index[3]: Unbound
indexPath for object at index[3]:(null)
indexPath passed to method: <NSIndexPath 0x64ddea0> 2 indexes [0, 2]

After executing the NSLog statements, I get an exception at the last line using [fetchedResultsController objectAtIndexPath:indexPath]. It happens for other index values too, but they always look valid.

*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'no object at index 2 in section at index 0'

So, to summarize, there appear to be the right number of fetched objects, there is one section (0), I can access each one by one method, but not by the other. The indexPathForObject: is always returning (null).

Is this a bug or am I misunderstanding something?


UPDATE

Here is the code, implementing the NSFetchedResultsControllerDelegate protocol methods.

- (void) controllerWillChangeContent:(NSFetchedResultsController *)controller {
    NSLog(@"Favorites controllerWillChangeContent");
    [self.tableView beginUpdates];
}

- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller 
{
    NSLog(@"Favorites Table controllerDidChangeContent");
    [self.tableView endUpdates];
}

- (void)controller:(NSFetchedResultsController *)controller 
   didChangeObject:(id)anObject 
       atIndexPath:(NSIndexPath *)indexPath 
     forChangeType:(NSFetchedResultsChangeType)type 
      newIndexPath:(NSIndexPath *)newIndexPath {

    NSLog(@"Favorites Changed Object");

    switch (type) {
        case NSFetchedResultsChangeInsert:
            NSLog(@"--- Favorite was inserted");
            if ([[self.fetchedResultsController fetchedObjects] count] == 1) {
                // configure first cell to replace the empty list indicator by first deleting the "empty" row
                [self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationNone];
            }

            [self.tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationNone];

            break;

        case NSFetchedResultsChangeDelete:
            NSLog(@"--- Favorite was deleted");

            [self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationNone];
            if ([[self.fetchedResultsController fetchedObjects] count] == 0) {
                // configure first cell to show that we have an empty list
                [self.tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationNone];
            }

            break;

        case NSFetchedResultsChangeMove:
            NSLog(@"--- Favorite was moved");

            break;

        case NSFetchedResultsChangeUpdate:
            NSLog(@"--- Favorite was updated");
            [self configureCell:(ResultCell*)[tableView cellForRowAtIndexPath:indexPath] atIndexPath:indexPath];

            break;

        default:
            break;
    }

}

- (void)controller:(NSFetchedResultsController *)controller
  didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo 
           atIndex:(NSUInteger)sectionIndex 
     forChangeType:(NSFetchedResultsChangeType)type {

    switch (type) {
        case NSFetchedResultsChangeInsert:
            NSLog(@"Favorites Section Added");

            break;

        case NSFetchedResultsChangeDelete:
            NSLog(@"Favorites Section Deleted");

            break;

        default:
            break;
    }

}

UPDATE 2

I don't know if it matters, but the tableView is initialized with this line:

    tableView = [[UITableView alloc] initWithFrame:CGRectMake(...) style:UITableViewStyleGrouped];

UPDATE 3

When I change the offending line as follows, it works fine. But I would rather keep the indexing the same as it is with the table.

//SearchResult *result = [self.fetchedResultsController objectAtIndexPath:indexPath];
SearchResult *result = [[self.fetchedResultsController fetchedObjects] objectAtIndex:[indexPath indexAtPosition:1]]
Jim
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  • how did you insert the object? Can you post the code where you are adding the object to your core data store and add the row to your tableView? – timthetoolman Nov 05 '11 at 06:34
  • are you actually adding something to the Core Data Store or just adding a row to the tableView? – timthetoolman Nov 05 '11 at 07:10
  • 1
    Yes, I do a save to the managed object context when I make changes. That's what triggers the calls to the NSFetchedResultsControllerDelegate protocol methods. – Jim Nov 05 '11 at 07:26
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    If you have an answer, the answer should not be inserted into the question but into an answer and then selected. – Peter DeWeese Jul 10 '14 at 21:05
  • Hi @Jim I know this is a pretty old post, but did you find a better solution than calling `[[self.fetchedResultsController fetchedObjects] objectAtIndex:...]` ? – Martin Nov 27 '15 at 10:55

1 Answers1

0

I had the same problem now.

For me it helped to initialise NSFetchedResultsController with cacheName: nil.