Image background service

NSData * imageData = [[NSData alloc] initWithContentsOfURL: [NSURL URLWithString: @"image url"]];

    cell.image = [UIImage imageWithData: imageData];

change to

dispatch_async(dispatch_get_global_queue(0,0), ^{

        NSData * data = [[NSData alloc] initWithContentsOfURL: [NSURL URLWithString: @"image url"]];

        if ( data == nil )

            return;

        dispatch_async(dispatch_get_main_queue(), ^{

            // WARNING: is the cell still using the same data by this point??

            cell.image = [UIImage imageWithData: data];

        });

    });

Reload particular row and section

Row:  

[self.tablename beginUpdates];

 NSIndexPath *indexPath = [NSIndexPath indexPathForRow:row inSection:section];

 NSArray *indexPaths = [[NSArray alloc] initWithObjects:indexPath, nil];

[self.tablename reloadRowsAtIndexPaths:indexPaths withRowAnimation:UITableViewRowAnimationNone];

 [self.tablename endUpdates];

         (OR)

// Build the two index paths
[self.tablename beginUpdates];

NSIndexPath* indexPath1 = [NSIndexPath indexPathForRow:3 inSection:2];

NSIndexPath* indexPath2 = [NSIndexPath indexPathForRow:4 inSection:3];

// Add them in an index path array

NSArray* indexArray = [NSArray arrayWithObjects:indexPath1, indexPath2, nil];

// Launch reload for the two index path

[self.tablename reloadRowsAtIndexPaths:indexArray withRowAnimation:UITableViewRowAnimationFade];
 [self.tablename endUpdates];

Section:

[self.tablename beginUpdates];

[self.tablename reloadSections:[NSIndexSet indexSetWithIndex:section] withRowAnimation:UITableViewRowAnimationNone];

[self.tablename endUpdates];

                (OR)

 [self.tablename beginUpdates];

 NSRange range = NSMakeRange(0, [self numberOfSectionsInTableView:self.tablename]);

 NSIndexSet *sections = [NSIndexSet indexSetWithIndexesInRange:range];

 [self.tablename reloadSections:sections withRowAnimation:UITableViewRowAnimationFade];
 [self.tablename endUpdates];