NSFetchedResultsController delegate fires methods only on first app launch - ios

Question

Sorry for my terrible english.
I have big problem in my iOS app. Application has big database which is managed by Core Data. And I have many TableView Controllers for displaying this data. Any change in database should be shown in tableview. It can be reached by implementing NSFetchedResultsController delegate protocol. All realization are very simple like in books. If application starts in simulator first time and I add new entries in some tables next delegate methods are successfully fired:
– controllerWillChangeContent:
– controller:didChangeObject:atIndexPath:forChangeType:newIndexPath:
– controllerDidChangeContent:
After stop debugging and start application again none of listed methods are fired.
They calls only after [managedObjectContext save] operation will perform.
Have you any ideas why this happens?
Source code:
//IssueProfileViewController.h class implements NSFetchedResultController delegate methods
- (NSFetchedResultsController*)fetchedResultsController{
if (_fetchedResultsController == nil) {
NSManagedObjectContext *managedObjectContext = self.issue.managedObjectContext;
NSFetchRequest *aFetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription entityForName:#"IssueHistoryItem" inManagedObjectContext:managedObjectContext];
[aFetchRequest setEntity:entity];
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:#"created" ascending:NO];
NSArray *sortDescriptors = [[NSArray alloc] initWithObjects:sortDescriptor, nil];
//NSPredicate *predicate = [[NSPredicate predicateWithFormat:#"issue == %# && isComment == NO", self.issue] retain];
NSPredicate *predicate = [NSPredicate predicateWithFormat:#"issue == %# && isComment == NO", self.issue];
[aFetchRequest setSortDescriptors:sortDescriptors];
[aFetchRequest setPredicate:predicate];
NSFetchedResultsController *aFetchedResultsController =
[[NSFetchedResultsController alloc] initWithFetchRequest:aFetchRequest
managedObjectContext:managedObjectContext
sectionNameKeyPath:nil
cacheName:nil];
[aFetchRequest release];
//[predicate release];
[sortDescriptors release];
[sortDescriptor release];
_fetchedResultsController = aFetchedResultsController;
_fetchedResultsController.delegate = self;
}
return _fetchedResultsController;
}
-(void)controllerWillChangeContent:(NSFetchedResultsController *)controller {
[self.tableView beginUpdates];
}
-(void)controllerDidChangeContent:(NSFetchedResultsController *)controller {
[self.tableView endUpdates];
}
-(void)controller:(NSFetchedResultsController *)controller
didChangeObject:(id)anObject
atIndexPath:(NSIndexPath *)indexPath
forChangeType:(NSFetchedResultsChangeType)type
newIndexPath:(NSIndexPath *)newIndexPath {
NSArray *paths;
// NSIndexSet *section = [NSIndexSet indexSetWithIndex:[newIndexPath section]];
NSIndexPath *cellContentIndexPath;
switch (type) {
case NSFetchedResultsChangeInsert:
// paths = [NSArray arrayWithObject:newIndexPath];
if (![anObject isKindOfClass:[ChangeIssueDimensionValueHistoryItem class]]) {
cellContentIndexPath = [NSIndexPath indexPathForRow:newIndexPath.row inSection:newIndexPath.section];
paths = [NSArray arrayWithObject:cellContentIndexPath];
[self.tableView insertRowsAtIndexPaths:paths
withRowAnimation:UITableViewRowAnimationFade];
[self sendMessageAboutObjectsCountChanged];
}
break;
case NSFetchedResultsChangeDelete:
paths = [NSArray arrayWithObject:indexPath];
[self.tableView deleteRowsAtIndexPaths:paths
withRowAnimation:UITableViewRowAnimationFade];
[self sendMessageAboutObjectsCountChanged];
break;
case NSFetchedResultsChangeMove:
[self.tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath]
withRowAnimation:UITableViewRowAnimationFade];
[self.tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath]
withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeUpdate:
[self configureCell:[self.tableView cellForRowAtIndexPath:indexPath]
withIssueHistoryItem:[self.fetchedResultsController objectAtIndexPath:indexPath]];
break;
default:
break;
}
}

Answer 1

That seems to be the proper way that the NSFetchedResultsController performs--responding to changes at the model layer (i.e. [managedObjectContext save]).
In the documentation: https://developer.apple.com/library/ios/#documentation/CoreData/Reference/NSFetchedResultsController_Class/Reference/Reference.html under 'Responding to Changes' it states that the controller will not show changes until the managed object's context has received a processPendingChanges message. That message can be triggered manually, also.