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POCoreData Fetch Crashes if used with dispatch_async
 

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  1. POCoreData Fetch Crashes if used with dispatch_async
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    <p>I have a core-data app that runs without crashing if I perform a fetch inside <code>viewDidLoad</code> like this:</p> <pre><code>- (void) performCoreDataFetch { NSError *error; if (![[self fetchedResultsController] performFetch:&amp;error]) { exit(-1); // Fail } } - (void)viewDidLoad { [super viewDidLoad]; [self performCoreDataFetch]; } </code></pre> <p>The only problem with the above way of performing fetch is if the data to be returned is big, it freezes the app for a few seconds (but does return correct result without crashing every single time), so to avoid that I decided to use dispatch_async (code shown below) and call <code>[self performCoreDataFetch]</code> inside it.</p> <p>But if I run this same [self performCoreDataFetch] inside dispatch_sync <strong>within viewDidLoad</strong>, like shown below,:</p> <pre><code>dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{ [self performCoreDataFetch]; dispatch_async(dispatch_get_main_queue(), ^{ [self.tableView reloadData]; }); }); </code></pre> <p>Calling <code>[self performCoreDataFetch]</code> within dispatch_async crashes the app randomly saying "<code>-[NSFetchRequest fetchLimit]: message sent to deallocated instance</code>"</p> <p>My fetchedResultsController method looks like this:</p> <pre><code>- (NSFetchedResultsController *)fetchedResultsController { if (fetchedResultsController != nil) { return fetchedResultsController; } // Create and configure a fetch request with the Organization entity NSFetchRequest *request = [[NSFetchRequest alloc] init]; request.entity = [NSEntityDescription entityForName:@"Organization" inManagedObjectContext:managedObjectContext]; request.fetchBatchSize = 20; // create sortDescriptor array NSSortDescriptor *nameDescriptor = [[NSSortDescriptor alloc] initWithKey:@"name" ascending:YES selector:@selector(caseInsensitiveCompare:)]; NSArray *sortDescriptorArray = [NSArray arrayWithObjects:nameDescriptor, nil]; request.sortDescriptors = sortDescriptorArray; NSPredicate *predicate = nil; predicate = [NSPredicate predicateWithFormat:@"state LIKE %@", filterByState]; [request setPredicate:predicate]; // Create and initialize the fetchedResultsController NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc ] initWithFetchRequest:request managedObjectContext:managedObjectContext sectionNameKeyPath:@"uppercaseFirstLetterOfName" cacheName:nil]; self.fetchedResultsController = aFetchedResultsController; fetchedResultsController.delegate = self; // Memory management filterByState = nil; // [sortDescriptorArray release]; [nameDescriptor release]; // [predicate release]; [request release]; [aFetchedResultsController release]; return fetchedResultsController; } </code></pre>
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    1. COWhat are you trying to accomplish? You should not have to call the `performFetch` method yourself...
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      1. USMundi
    2. COWithout a performFetch,I don't know of another way to execute a core data fetch.
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    3. COWhat are you trying to accomplish? If you initialize the fetched results controller lazily, the fetch will be done there without you having to call `performFetch` yourself. Again, what are you trying to do with the fetch?
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