Why old value appeared in tableViewCell - ios

Question

I added a UILabel when TableViewCell making. Code like this:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
Special *special = [speciales objectAtIndex:indexPath.row];
......
UILabel *description = [[UILabel alloc] initWithFrame:CGRectMake(80, 21, 220, 50)];
description.text = special.specialDescription;
description.font = [UIFont fontWithName:#"Heiti SC" size:12];
description.textColor = [UIColor darkGrayColor];
description.lineBreakMode = UILineBreakModeWordWrap;
description.numberOfLines = 3;
[cell addSubview:description];
return cell;
}
It works well, but when I scrolled it from the bottom to top, and when I selected a row, the old value appeared at the same time. Who can help me fix this?
Thank you!
update : All of my codes is this:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
Special *special = [speciales objectAtIndex:indexPath.row];
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
UIImageView *img = [[UIImageView alloc] initWithFrame:CGRectMake(10, 5, 60, 60)];
img.image = special.specialIconImage;
[self addShadowToImage:img];
[cell addSubview:img];
UILabel *name = [[UILabel alloc] initWithFrame:CGRectMake(80, 5, 220, 16)];
name.text = special.specialName;
name.font = [UIFont fontWithName:#"Heiti SC" size:16];
[cell addSubview:name];
UILabel *description = [[UILabel alloc] initWithFrame:CGRectMake(80, 21, 220, 50)];
description.text = special.specialDescription;
description.font = [UIFont fontWithName:#"Heiti SC" size:12];
description.textColor = [UIColor darkGrayColor];
description.lineBreakMode = UILineBreakModeWordWrap;
description.numberOfLines = 3;
[cell addSubview:description];
return cell;
}

Answer 1

The problem is that you're adding the Image and Label subviews every time the cell is being called. Instead, you only want to add those subviews when you're creating the cell. Every time the cell gets called you just want to set the values of subviews. You'll want something like this (done off memory):
Special *special = [speciales objectAtIndex:indexPath.row];
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(10, 5, 60, 60)];
[imageView setTag:100];
[cell addSubview:imageView];
UILabel *nameLabel = [[UILabel alloc] initWithFrame:CGRectMake(80, 5, 220, 16)];
name.font = [UIFont fontWithName:#"Heiti SC" size:16];
[nameLabel setTag:101];
[cell addSubview:nameLabel];
UILabel *descriptionLabel = [[UILabel alloc] initWithFrame:CGRectMake(80, 21, 220, 50)];
[descriptionLabel setTag:102];
descriptionLabel.font = [UIFont fontWithName:#"Heiti SC" size:12];
descriptionLabel.textColor = [UIColor darkGrayColor];
descriptionLabel.lineBreakMode = UILineBreakModeWordWrap;
descriptionLabel.numberOfLines = 3;
[cell addSubview:descriptionLabel];
}
UIImageView *img = (UIImageView *)[cell viewWithTag:100];
img.image = special.specialIconImage;
[self addShadowToImage:img];
UILabel *name = (UILabel *)[cell viewWithTag:101];
name.text = special.specialName;
UILabel *description = (UILabel *)[cell viewWithTag:102];
description.text = special.specialDescription;
return cell;

Answer 2

[tableView reloadData];
try this.

Answer 3

While I think you should be dequeueing cells to reuse them, it doesn't seem to be the root of your problem - unless you are reusing cells and didn't show us. There could be code there that points to the issue.
I think the issue could be related to redrawing. Try putting this at the end of your tableView:cellForRowAtIndex: method
[cell setNeedsDisplay];
This will force the UI to redraw the cell.

Answer 4

What does ..... mean in the code?
Are you using dequeueReusableCellWithIdentifier in there?
If That part of the code conaitns the code something like below, then It should work just fine-
UITableViewCell * cell = [tableView dequeueReusableCellWithIdentifier:#"Cell"];
if(cell == nil)
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:#"Cell"];

Answer 5

Here are some things to keep in mind:
• The new views must be added when we instantiate a new cell, but not when we
reuse a cell (because a reused cell already has them).
• We must never send addSubview: to the cell itself — only to its contentView (or
some subview thereof).
• We should assign the new views an appropriate autoresizingMask, because the
cell’s content view might be resized.
• Each new view should be assigned a tag so that it can be referred to elsewhere.
Here is code:
//thanks to Thomas Hajcak's code
Special *special = [speciales objectAtIndex:indexPath.row];
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil) {
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
UIImageView *imageView = [[UIImageView alloc] initWithFrame:CGRectMake(10, 5, 60, 60)];
[imageView setTag:100];
//autoresizingMask as follow
imageView.autoresizingMask = (UIViewAutoresizingFlexibleHeight |
UIViewAutoresizingFlexibleLeftMargin);
[cell.contentView addSubview:imageView];
UILabel *nameLabel = [[UILabel alloc] initWithFrame:CGRectMake(80, 5, 220, 16)];
name.font = [UIFont fontWithName:#"Heiti SC" size:16];
[nameLabel setTag:101];
[cell.contentView addSubview:nameLabel];
UILabel *descriptionLabel = [[UILabel alloc] initWithFrame:CGRectMake(80, 21, 220, 50)];
[descriptionLabel setTag:102];
descriptionLabel.font = [UIFont fontWithName:#"Heiti SC" size:12];
descriptionLabel.textColor = [UIColor darkGrayColor];
descriptionLabel.lineBreakMode = UILineBreakModeWordWrap;
descriptionLabel.numberOfLines = 3;
[cell.contentView addSubview:descriptionLabel];
}
UIImageView *img = (UIImageView *)[cell.contentView viewWithTag:100];
img.image = special.specialIconImage;
[self addShadowToImage:img];
UILabel *name = (UILabel *)[cell.contentView viewWithTag:101];
name.text = special.specialName;
UILabel *description = (UILabel *)[cell.contentView viewWithTag:102];
description.text = special.specialDescription;
return cell;