CODEWITHSUNDEEP
iosobjective-ccore-datansfetchedresultscontroller
Slayter
Slayter

Reputation: 1170

NSFetchedResultsController won't change on reloadData

I have an iOS app in Master-Detail form where posts made by users are shown in the master view and comments shown in the detail. When I select a post I can see all of the comments just fine but when I go back and select another post, the data does not change to the comments for the next post.

I call this in viewDidLoad

 self.fetchedResultsController = nil;
 [self.tableView reloadData];

But nothing happens.

Here is my code for fetchedResultsController

- (NSFetchedResultsController *)fetchedResultsController
{
    if (_fetchedResultsController != nil) {
        return _fetchedResultsController;
    }

    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    // Edit the entity name as appropriate.
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"Comment" inManagedObjectContext:self.managedObjectContext];
    [fetchRequest setEntity:entity];

    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"question == %@", self.detailItem];
    [fetchRequest setPredicate:predicate];

    // Set the batch size to a suitable number.
    [fetchRequest setFetchBatchSize:20];

    // Edit the sort key as appropriate.
    NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:@"creator" ascending:YES];
    NSArray *sortDescriptors = @[sortDescriptor];

    [fetchRequest setSortDescriptors:sortDescriptors];

    // Edit the section name key path and cache name if appropriate.
    // nil for section name key path means "no sections".
    NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:self.managedObjectContext sectionNameKeyPath:nil cacheName:@"Master"];
    aFetchedResultsController.delegate = self;
    self.fetchedResultsController = aFetchedResultsController;

    NSError *error = nil;
    if (![self.fetchedResultsController performFetch:&error]) {
        // Replace this implementation with code to handle the error appropriately.
        // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
        NSLog(@"Unresolved error in detail %@, %@", error, [error userInfo]);
        abort();
    }

    return _fetchedResultsController;
}

Upvotes: 2

Views: 2175

Answers (3)

Audun Kjelstrup
Audun Kjelstrup

Reputation: 1430

The reason your fetched-results-controller doesn't refresh is because you have set a cache. You will either need to pass nil as your cache-name, or delete the cache prior to refreshing the FRC:

  [NSFetchedResultsController deleteCacheWithName:@"Master"]

Upvotes: 6

Mark Struzinski
Mark Struzinski

Reputation: 33471

Have you tried calling your reset code in viewDidAppear instead? viewDidLoad is typically not called multiple times in the view's lifecycle. viewWillAppear/viewDidAppear are called when the view is actually coming on screen.

Have you tried to breakpoint your table reload method to make sure it's actually being called?

Upvotes: 2

Shah Paneri
Shah Paneri

Reputation: 739

Just try this code:

before calling this method don't forget to write self.fetchedResultsController = nil;

- (NSFetchedResultsController *)fetchedResultsController // attaches an NSFetchRequest to this UITableViewController
{
    if (_fetchedResultsController != nil )
    {
        return _fetchedResultsController;
    }

    NSLog(@"Length:: %d",[[_fetchedResultsController mutableCopy] length]);

    NSFetchRequest *fetchRequest = [NSFetchRequest fetchRequestWithEntityName:@"Comment"];
    [fetchRequest setIncludesSubentities:YES];

    // Sort by Application name
    NSSortDescriptor* sortDescriptor1 = [[NSSortDescriptor alloc] initWithKey:@"creator" ascending:YES selector:@selector(localizedCaseInsensitiveCompare:)];
    //Sort by CommandNameloca
    NSArray* sortDescriptors = [[NSArray alloc] initWithObjects: sortDescriptor1, nil];
    [fetchRequest setSortDescriptors:sortDescriptors];

    [fetchRequest setFetchBatchSize:100];

    ordersArr=[[NSMutableArray alloc]initWithArray:sortDescriptors];

    NSLog(@"----- ordersArr Count == %d",[ordersArr count]);

    NSFetchedResultsController *aFetchedResultsController = [[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest managedObjectContext:self.managedObjectContext sectionNameKeyPath:@"creator" cacheName:@"Master"];
    aFetchedResultsController.delegate = self;
    self.fetchedResultsController = aFetchedResultsController;

    NSError *error = nil;

    if (![self.fetchedResultsController performFetch:&error])
    {
        // Replace this implementation with code to handle the error appropriately.
        // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
        NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
        abort();
    }
    return _fetchedResultsController;
}

Upvotes: 1

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