NSFetchedResultsController objectAtIndex, objectAtIndexPath, indexPathForObject inconsistencies - objective-c

Question

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]]

Answer 1

I had the same problem now.
For me it helped to initialise NSFetchedResultsController with cacheName: nil.