iPhone cellForRowAtIndexPath returns cached cell

Question

Hi,

When i add a label to a cell using:

- (void)tableView:(UITableView *)tableView accessoryButtonTappedForRowWithIndexPath:(NSIndexPath *)indexPath{
    UITableViewCell *cell = [tableView cellForRowAtIndexPath:indexPath];
    [cell addSubView:someLabel];
}

It adds the label to multple cells, because it adds the label to a cached cell. So every cell in the tableView thats uses a cached cell, will display my label.

Does somebody knows a way around? Ton

Answer 1

You'll need to keep track of whether or not each cell has the label currently applied. In cellForRowAtIndexPath: check if it should be there, if so then add it if necessary, else remove it if necessary.

Answer 2

If your cell is a subclass of UITableViewCell, you can override - (void)prepareForReuse which gets called just before the cell is returned from - (UITableViewCell *)dequeueReusableCellWithIdentifier:(NSString *)identifier

This is the way to provide a 'clean slate' for your cells, but only the cached ones that are about to be reused.

Answer 3

Give unique identifier name like:

// Customize the appearance of table view cells.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath 
{

    static NSString *CellIdentifier = NSLocalizedString(@"Cell",@"");
…
}

instead of giving constatnt identifier name, give your own unique identifier name like:

// Customize the appearance of table view cells.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath 
{

    static NSString *CellIdentifier = [self getuniqueID];
...
}

This will solve your problem.

Answer 4

Why not just simplify things and just hide the label by default and include it on all the cells.

When you tap the cell, then instead of adding a view - just show the one that is there but hidden.

When you are done, hide the label.

Answer 5

I sometimes use this code: (When the cell != nil)

NSArray *subviews = [[NSArray alloc] initWithArray:cell.contentView.subviews];
for (UIView *subview in subviews) {
    [subview removeFromSuperview];
}
[subviews release];

It removes all subviews of an cached cell. Dont know if it is a performance hog, but I havent hade any problems.