dequeueReusableCellWithIdentifier not working with ARC and IOS 4 - iphone

Question

I can't seem to get dequeueReusableCellWithIdentifier working.
I need to build a project for IOS 4 so I can't use storyboards, but I'm using ARC.
Let's say I have 2 sections, each with 1 row.
Looking at the code below, I'm using the strong property to pass ownership, since ARC would insert the "autorelease" code.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *cellIdentifier = #"TableCellIdentifier";
MainTableCell *cell = (MainTableCell *)[tableView dequeueReusableCellWithIdentifier:cellIdentifier];
if (cell == nil)
{
self.retainedCell = [[MainTableCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier];
}
[self configureCell:cell atIndexPath:indexPath];
return cell;
}
However, for each row, cell is always nil (and hence a new MainTableCell is alloc'd) each time the function is called. The cell is never re-used.
This wouldn't be so much a problem except I programmatically call tableView:cellForRowAtIndexPath:, meaning I get a newly alloc'd cell each time, rather than the existing cell.
The only method I can see is to add the cells to an NSMutableArray.
Is there something I'm missing with dequeueReusableCellWithIdentifier now?
Thanks!
EDIT
I'm using the code below to get the cell. As mentioned it's creating a new cell not re-using the one that should have been already made + retained.
I don't need to invoke reloadData for all the rows, just change a specific one.
MainTableCell *cell = (MainTableCell *)[self tableView:self.tableView cellForRowAtIndexPath:[NSIndexPath indexPathForRow:0 inSection:0]];
[self configureCell:cell atIndexPath:indexPath];

Answer 1

You happen to be de-queuing MainTableCell, and then you proceed to check if it is nil, at which point you use a completely different var to alloc a table cell. What the heck? Try this:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *cellIdentifier = #"TableCellIdentifier";
MainTableCell *cell = (MainTableCell *)[tableView dequeueReusableCellWithIdentifier:cellIdentifier];
if (cell == nil)
{
cell = [[MainTableCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier];
}
[self configureCell:cell atIndexPath:indexPath];
return cell;
}