dequeueReusableCellWithIdentifier:
only returns a cell
if it has been marked as ready for reuse. This is why in almost every cellForRowAtIndexPath:
method you will see something like
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (nil == cell) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault
reuseIdentifier:CellIdentifier];
}
// Do something to cell
return cell;
In effect, enough rows will be allocated to fill the visible part of the tableview
(plus one or two more). As cells scroll
off screen, they are removed from the table
and marked as ready for reuse
. As the queue of “available cells” grows, your line that asks for a dequeued cell
will start obtaining a cell
to use, at which point you will not have to allocate anymore.