How to refresh a UITableViewController or NSFetchedResultsController?
I have a little problem with my UITableViewController or NSFetchedResultsController. I am not sure which is the problem soure but I guess its the UITableViewController.
As I said I use a NSFetchedResultsController to fill my data into a UITableViewController. The data is sorted by date and is also displayed in sections by date-year, eg May 2010/June 2010/ and so on. This is displayed as the section header.
Now when I add new data, it automatically uses the current date as default, but if I want to use a date, that is currently not in the section list, eg April 2010 (currently May and June in the list), then this is not displayed correctly. Only when I quit the app and start it again it will show the new section headers and everything is fine.
So I somehow need to be able to refresh my list or update it. By just adding it to the context and changing it does not seem to update it.
Again, I am not sure what I need to update, if it is my NSFetchedResultsController object or the UITableViewController.
UPDATE #1:
I just figured that there is an exception in this method :
- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller
{
// The fetch controller has sent all current change notifications, so tell the table view to process all updates.
[self.tableView endUpdates];
}
This is where I move the data :
- (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type newIndexPath:(NSIndexPath *)newIndexPath
{
UITableView *tableView = self.tableView;
switch(type)
{
case NSFetchedResultsChangeInsert:
[tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeDelete:
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
break;
case NSFetchedResultsChangeUpdate:
// [self configureCell:[tableView cellForRowAtIndexPath:indexPath] atIndexPath:indexPath];
break;
case NSFetchedResultsChangeMove:
[tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
// Reloading the section inserts a new row and ensures that titles are updated appropriately.
[tableView reloadSections:[NSIndexSet indexSetWithIndex:newIndexPath.section] withRowAnimation:UITableViewRowAnimationFade];
break;
}
}
This method is pretty much taken from the CoreDataBooks example from Apple. And this is the error :
Serious application error. An exception was caught from the delegate of NSFetchedResultsController during a call to -controllerDidChangeContent:. *** -[NSMutableArray removeObjectAtIndex:]: index 1 beyond bounds [0 .. 0] with userInfo (null)
And after that, the edit mode (where the delete button appears) does not work anymore.
Thanks.
Ok, looks like I found a solution, I just skip these
[self.tableView beginUpdates];
[self.tableView endUpdates];
and always do this.
- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller
{
[self.tableView reloadData];
}
I will obviously give this some more logic, since the problem only occures when I want to move my data in a section that does not exist before. Until someone can give me a real solution, I will go with this one.
Adopting the fix by Apple in iPhoneCoreDataRecipes in version 1.2, the proper thing to do is to replace
// Reloading the section inserts a new row and ensures that titles are updated appropriately.
[tableView reloadSections:[NSIndexSet indexSetWithIndex:newIndexPath.section] withRowAnimation:UITableViewRowAnimationFade];
with
[tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationFade];
(FileMerge is your friend!)
Note, there's another fix in version 1.2 that prevents erratic crashing when creating new entries. I had reported this and it was fixed within two weeks. I encourage you to file bug reports with Apple. They're far more responsive than you think, and you can expect to get the best possible fix.
You need to implement the controller:didChangeSection:atIndex:forChangeType: delegate methods. In it, send insertSections:withRowAnimation: , deleteSections:withRowAnimation: , and reloadSections:withRowAnimation: messages to your table view depending on the reported change type.
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