iphone - labels in custom cell overlaps

Question

I have customized the cell with four labels, initially it looks fine but when I scroll and then select a cell labels from another row overlaps. here is my code. Any help will be highly appreciated.

 -(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath{
static NSString *CellIdentifier=@"CellIdentifier";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier: CellIdentifier];

if (cell == nil) { cell = [[[UITableViewCell alloc]
                            initWithStyle:UITableViewCellStyleDefault 
                            reuseIdentifier: CellIdentifier] autorelease];
}
 NSString *cellIconName = [[self cellIcon] objectAtIndex:[indexPath row]];
cellImage=[UIImage imageNamed:cellIconName];

cell.imageView.image=cellImage;

UILabel *labelOne = [[UILabel alloc]initWithFrame:CGRectMake(65, 10, 140, 20)];
labelOne.text = [[NSString alloc]initWithFormat:@"%@",[dataList objectAtIndex:indexPath.row]];
[cell.contentView addSubview:labelOne];
[labelOne release];

UILabel *labelTwo = [[UILabel alloc]initWithFrame:CGRectMake(260, 10, 140, 20)];
labelTwo.text = [[NSString alloc]initWithFormat:@"%@",[newPrice objectAtIndex:indexPath.row]];
[cell.contentView addSubview:labelTwo];
[labelTwo release];



UILabel *label3 = [[UILabel alloc]initWithFrame:CGRectMake(65, 30, 140, 20)];
label3.text=[[NSString alloc]initWithFormat:@"%@",[details objectAtIndex:indexPath.row]];
[cell.contentView addSubview:label3];
[label3 release];


UILabel *label4 = [[UILabel alloc]initWithFrame:CGRectMake(260, 30, 140, 20)];
label4.text=[[NSString alloc]initWithFormat:@"%@",[oldPrice objectAtIndex:indexPath.row]];
[cell.contentView addSubview:label4];
[label4 release];

return cell;

}

Answer 1

The mistake is you allocated the labels in (else part)outside of the if condition if(cell==nil). You should only create the labels once, when the cell is first created.

When we run the code the control checks whether the cell is nil or have any values. If we allocate the label in else part every time (while scrolling also) you are creating a new label every time. If we allocate it in if condition, the label is only allocated once for each cell and we just update the text value when scrolling.

-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier=@"CellIdentifier";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier: CellIdentifier];

if (cell == nil) 
{ 
cell = [[[UITableViewCell alloc]
? ? ? ? ? ? ? ? ? ? ? ? ? ? initWithStyle:UITableViewCellStyleDefault 
? ? ? ? ? ? ? ? ? ? ? ? ? ? reuseIdentifier: CellIdentifier] autorelease];

NSString *cellIconName = [[self cellIcon] objectAtIndex:[indexPath row]];
cellImage=[UIImage imageNamed:cellIconName];

cell.imageView.image=cellImage;

UILabel *labelOne = [[UILabel alloc]initWithFrame:CGRectMake(65, 10, 140, 20)];
labelOne.tag = 100;
[cell.contentView addSubview:labelOne];
[labelOne release];

UILabel *labelTwo = [[UILabel alloc]initWithFrame:CGRectMake(260, 10, 140, 20)];
labelTwo.tag = 101;
[cell.contentView addSubview:labelTwo];
[labelTwo release];

}

UILabel *labelOne = (UILabel *) [cell.contentView viewWithTag:100];
labelOne.text = [dataList objectAtIndex:indexPath.row];

UILabel *labelTwo = (UILabel *) [cell.contentView viewWithTag:101];
labelTwo.text = [newPrice objectAtIndex:indexPath.row];
?

return cell;
}