How to edit label in custom UITableViewCell?

Question

Hi, I'm a newby in iPhone programming, I have created a custom UITableViewCell with 3 labels and I have populated an UITableView with some rows. I need to change the text of one of the labels when the user select the cell.
I wrote this:
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = @"Cell";
UITableViewCell *theCellSelected = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
theCellSelected = [theTableView cellForRowAtIndexPath:indexPath.row];
UILabel *theLabelToEdit = (UILabel *)[theCellSelected viewWithTag:1];
theLabelToEdit.text = @"Some Text..";
..but nothing happen to the label, the text doesn't change..
What's wrong?
Thank you!
PS: sorry for my english, I'm italian and I don't speak it very well..

Answer 1

Hi Zoodany, and welcome to the Dev Forum!
zoodany wrote:
I wrote this:
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
theTableView = tableView;
// remove --> static NSString *CellIdentifier = @"Cell";
UITableViewCell *theCellSelected;
// remove --> = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
theCellSelected = [theTableView cellForRowAtIndexPath:indexPath]; // <-- remove '.row'
UILabel *theLabelToEdit = (UILabel *)[theCellSelected viewWithTag:1];
theLabelToEdit.text = @"Some Text..";
Assuming your @interface, xib and DataSource methods are consistent with the above, the only thing stopping your code from working would be the 'indexPath.row' arg as commented. The lines which dequeue a cell won't prevent your code from running, though if any cells are actually in the queue, you'll have a memory leak there.
However, I doubt the code you posted is the same as the code you tested. If you actually coded cellForRowAtIndexPath:indexPath.row, you should have gotten a warning since 'row' is an int instead of a pointer. And if you had ignored that warning the program would have crashed at that line. This kind of mixup often happens when the programmer keys code into the forum instead of pasting it directly from the source file. Please copy and paste when posting your code here (also see the alert about formatting code, the first topic of the forum), ok?
If indeed 'indexPath.row' is a red herring, I think we need to look elsewhere in your project for the problem.
I have created a custom UITableViewCell
This contradicts your code somewhat. If you subclassed UITableViewCell, you'd normally add ivars with matching @properties to the custom cell so you could access the subviews as cell.label1, cell.label2, etc. Using viewWithTag to find one of the labels suggests that you simply added the labels to vanilla UITableViewCell objects rather that subclassing (adding the labels without subclassing is probably the best choice if no further customization is required).
So please let us know whether or not you actually defined a subclass of UITableViewCell. Assuming you didn't, here's an example of how to add labels to your cells (only two labels are added below to simplify the example):
// Customize the appearance of table view cells.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = @"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault
reuseIdentifier:CellIdentifier] autorelease];
// make label 1
UILabel *label = [[UILabel alloc] initWithFrame:CGRectMake(20, 3, 140, 38)];
label.text = @"Label 1";
label.backgroundColor = [UIColor lightGrayColor];
label.font = [UIFont boldSystemFontOfSize:20];
label.tag = 1;
[cell.contentView addSubview:label];
[label release];
// make label 2
label = [[UILabel alloc] initWithFrame:CGRectMake(160, 3, 140, 38)];
label.text = @"Label 2";
label.backgroundColor = [UIColor yellowColor];
label.font = [UIFont boldSystemFontOfSize:20];
label.tag = 2;
[cell.contentView addSubview:label];
[label release];
// Set up the cell...
return cell;
- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
UITableViewCell *theCellSelected = [tableView cellForRowAtIndexPath:indexPath];
UILabel *theLabelToEdit = (UILabel *)[theCellSelected viewWithTag:1];
theLabelToEdit.text = @"Some Text..";
Note that 'tableView' is used in the delegate method instead of an instance variable such as 'theTableView'. The 'tableView' parameter will always be set to the address of the table view which is calling the delegate method, so there's no need to use an ivar in this case. In fact, 'theTableView' could also be the cause of your problem. For example if you made the table view in IB, you might have forgotten to connect the 'theTableView' outlet of the controller (or File's Owner) to the UITableView object. So you might also check that connection, though the code above doesn't depend on it.
Hope that helps!
- Ray