In iOS 6, 2 new methods -registerClass:forCellReuseIdentifier: and -dequeueReusableCellWithIdentifier:forIndexPath: were added to UITableView.

Prior to this, you would write code like the following when you need a UITableView cell instance:

- (UITableViewCell*)tableView:(UITableView*)aTableView cellForRowAtIndexPath:(NSIndexPath*)indexPath {
    NSString* cellIdentifier = @"MyTableViewCellIdentifier";
    UITableViewCell* cell = aTableView.dequeueReusableCellWithIdentifier(cellIdentifier)
    if (!cell) {
      cell = [[UITableView alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellIdentifier];
    }

    //config cell
    return cell;
}

Starting with iOS 6, you can do this instead:

- (void)viewDidLoad {
    [super viewDidLoad];
    NSString* cellIdentifier = @"MyTableViewCellIdentifier";
    [self.tableView registerClass:[UITableViewCell class] forCellReuseIdentifier:cellIdentifier];
}

- (UITableViewCell*)tableView:(UITableView*)aTableView cellForRowAtIndexPath:(NSIndexPath*)indexPath {
    NSString* cellIdentifier = @"MyTableViewCellIdentifier";
    UITableViewCell* cell = aTableView.dequeueReusableCellWithIdentifier(cellIdentifier, forIndexPath:indexPath)
    //config cell. cell is always non-nil and the cell will have the correct height as returned by -tableView:heightForRowAtIndexPath:.
    return cell;
}

-dequeueReusableCellWithIdentifier:forIndexPath: always return a valid cell so we can skip the nil check. The cell will also have the correct height as returned by -tableView.heightForRowAtIndexPath:

Note that using this, all cells created will have the style UITableViewCellStyleDefault unless we use a UITableViewCell subclass.