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PONSFetchedResultsController attempting to insert nil object?
 

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    <p>For a long time I've been getting a strange bug where most of my table view becomes black (only a few cells remain <a href="http://cl.ly/LFlS" rel="nofollow">http://cl.ly/LFlS</a>) and in other views (connected to the same MOC) some other visual glitches appear: <a href="http://cl.ly/LH3c" rel="nofollow">http://cl.ly/LH3c</a> (notice the duplicate section headers). I always figured it was a bug with CoreData but I never got to reproduce it until today while it was hooked to the debugger. Here's the exception I got right before it happened:</p> <blockquote> <p>CoreData: error: Serious application error. An exception was caught from the delegate of NSFetchedResultsController during a call to -controllerDidChangeContent:. <em>*</em> -[__NSArrayM insertObject:atIndex:]: object cannot be nil with userInfo (null)</p> </blockquote> <p>It stopped on the <code>[tableView endUpdates]</code> line in my <code>controllerDidChangeContent:</code> method. Then if I click continue, the app doesn't crash, but user interaction becomes extremely sluggish. I looked all over the place as of what might be the cause of that exception and couldn't find anything. Any clue?</p> <p>My NSFetchedResultsController change handling looks pretty much like Apple's boilerplate. The init of my NSFRC looks like this:</p> <pre><code>NSFetchRequest *request = [[NSFetchRequest alloc] init]; NSEntityDescription *entity = [NSEntityDescription entityForName:@"Artist" inManagedObjectContext:[SWDataManager sharedManager].mainObjectContext]; [request setEntity:entity]; [request setFetchBatchSize:100]; NSSortDescriptor *sortByName = [[NSSortDescriptor alloc] initWithKey:@"sortName" ascending:YES selector:@selector(localizedCaseInsensitiveCompare:)]; [request setSortDescriptors:@[sortByName]]; fetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:request managedObjectContext:mainObjectContext sectionNameKeyPath:@"firstLetter" cacheName:nil]; fetchedResultsController.delegate = self; [self refreshDataSource]; // set fetch request predicate and call performFetch on NSFRC return fetchedResultsController; </code></pre> <p>EDIT: I can add that this definitely happened after that a bunch of objects got deleted from my MOC and therefore from the table view.</p> <p>As requested, my <code>controllerDidChangeContent:</code> code:</p> <pre><code>- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller { [self.tableView endUpdates]; // this updates the section index and footer cell and other kind of stuff [self performSelector:@selector(layoutSpecialCells) withObject:nil afterDelay:0.3]; } </code></pre>
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    1. USsamvermette
    1. USsamvermette
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      1. USMatthew Johnson
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    1. COYou will need to post your `-controllerDidChangeContent:`.
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      1. USMundi
    2. CO@Mundi added. Like I said, it's nothing special...
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    3. COAlso added screenshots of how my table views look after I get the exception.
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Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

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