Question

I’m trying to reorder UITableView in iOS application.
After harvesting a lot of StackOverFlow questions, I used this:

- (void)tableView:(UITableView *)tableView moveRowAtIndexPath:(NSIndexPath *)fromIndexPath toIndexPath:(NSIndexPath *)toIndexPath {
    self.userDrivenDataModelChange = YES;

    NSUInteger fromIndex = fromIndexPath.row;  
    NSUInteger toIndex = toIndexPath.row;

    NSManagedObject *affectedObject = [self.fetchedResultsController.fetchedObjects objectAtIndex:fromIndex];  
    [affectedObject setValue: [NSNumber numberWithInt:toIndex] forKey:@"priority"];

    NSUInteger start, end;
    int delta;

    if (fromIndex < toIndex) {
        // move was down, need to shift up
        delta = -1;
        start = fromIndex + 1;
        end = toIndex;
    } else { // fromIndex > toIndex
        // move was up, need to shift down
        delta = 1;
        start = toIndex;
        end = fromIndex - 1;
    }

    for (NSUInteger i = start; i <= end; i++) {
        NSManagedObject *otherObject = [self.fetchedResultsController.fetchedObjects objectAtIndex:i];  
        NSNumber *oldPriority = (NSNumber *)[otherObject valueForKey:@"priority"];
        int tmp = [oldPriority intValue] + delta;
        NSNumber *newPriority = [NSNumber numberWithInt:tmp];
        [otherObject setValue: [NSNumber numberWithInt:[newPriority intValue]] forKey:@"priority"];        
    }


    NSError *error = nil;
    if (! [self.fetchedResultsController.managedObjectContext save:&error]) {
        NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
        abort();
    }

    // Should I call something here?

    self.userDrivenDataModelChange = NO;
}

After sending save message to the context object, What should I call? some method on the fetch controller or the table view? because it is not working in the current shape.

Should I send save to the context object in the first place?

Answer 1

You’re already sending save message to managedObjectContext, which is fine, if (! [self.fetchedResultsController.managedObjectContext save:&error]).

To see updated results in table view, it’ll be probably sufficient to call [tableView reloadData]; at the end of this method.