Question

Ok Guys, here’s the situation I have.

I’m using a UITableViewController with Core Data. The table has about 200 cells, that basically function as a checklist. When you tap a cell, that cell has a checkbox that gets toggled set to the UITableViewCell.imageView ( the UIImageView assigned to the left of the label).

Anytime I use either of the two ways below to update the table, it takes about 1 – 2 seconds for the update … and from what I can tell, it seems to be reloading every cell. How can I force only the cell that was just tapped to be updated?

[self.tableView reloadData]; or

- (void)controllerWillChangeContent:(NSFetchedResultsController *)controller {
    [self.tableView beginUpdates];
}

- (void)controller:(NSFetchedResultsController *)controller didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo
           atIndex:(NSUInteger)sectionIndex forChangeType:(NSFetchedResultsChangeType)type {

    switch(type) {
        case NSFetchedResultsChangeInsert:
            [self.tableView insertSections:[NSIndexSet indexSetWithIndex:sectionIndex]
                          withRowAnimation:NO];
            break;

        case NSFetchedResultsChangeDelete:
            [self.tableView deleteSections:[NSIndexSet indexSetWithIndex:sectionIndex]
                          withRowAnimation:NO];
            break;
    }
}

- (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:NO];
            break;

        case NSFetchedResultsChangeDelete:
            [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath]
                             withRowAnimation:NO];
            break;

        case NSFetchedResultsChangeUpdate:
            [self configureCell:[tableView cellForRowAtIndexPath:indexPath]
                    atIndexPath:indexPath];
            break;

        case NSFetchedResultsChangeMove:
            [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath]
                             withRowAnimation:NO];
            [tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath]
                             withRowAnimation:NO];
            break;
    }
}

- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller {
    [self.tableView endUpdates];
}

Answer 1

You need this:

- (void)reloadRowsAtIndexPaths:(NSArray *)indexPaths withRowAnimation:(UITableViewRowAnimation)animation

http://developer.apple.com/iphone/library/documentation/uikit/reference/UITableView_Class/Reference/Reference.html#//apple_ref/doc/uid/TP40006943-CH3-SW40