Images change while scrolling the table in iphone? - iphone

Question

I'm using the xml for fetching the data and display it in the uitable. In the XML i have a separate tag for the image as "link". I'm displaying this image as the cell image. Everything workings fine when the applications loads, but when i scroll the table the images in the cell are getting changed.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = #"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (cell == nil)
{
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier] autorelease];
cell.accessoryType=UITableViewCellAccessoryNone;
cell.selectionStyle=UITableViewCellSelectionStyleNone;
//cell. separatorStyle=UITableViewCellSeparatorStyleNone;
titleLabel = [[UILabel alloc] initWithFrame:CGRectMake(110, 10, 190, 130)];
[titleLabel setTag:2];
titleLabel.numberOfLines=7;
[titleLabel setFont:[UIFont systemFontOfSize:14]];
[titleLabel setTextColor:[UIColor blackColor]];
[titleLabel setBackgroundColor:[UIColor clearColor]];
[cell.contentView addSubview:titleLabel];
[titleLabel release];
imageView= [[UIImageView alloc] initWithFrame:CGRectMake(5, 20, 90, 110)];
[cell.contentView addSubview:imageView];
}
NSDictionary *appRecord = [responseArr objectAtIndex:indexPath.row];
NSString *urlLink;
urlLink=[NSString stringWithFormat:#"%#",[appRecord objectForKey:#"link"]];
NSLog(#"LINK : %#",urlLink);
if([urlLink length] ==0)
{
imageView.image=[UIImage imageNamed:#"ioffer.png"];
}
else {
NSData *imageData = [NSData dataWithContentsOfURL:[NSURL URLWithString:urlLink]];
UIImage *image = [[UIImage alloc] initWithData:imageData];
imageView.image = image;
}
UILabel *desclbl = (UILabel*)[cell.contentView viewWithTag:2];
desclbl.text = [NSString stringWithFormat:#"%#",[appRecord objectForKey:#"description"]];
return cell;
}
I have used these code in the table's cellForRowAtIndexPath. responseArr is the array where i stored the links.
Can any one help me in this issue.
Thanks in advance
Malathi

Answer 1

If you reuse an existing table view cell, i.e. the code skips the first if-block, then imageView isn't initialized (where is it declared anyway?). That means even though you set a new text, some random image is reused.
The fix is to make sure that imageView is intialized in all cases.
And please do declare it locally in this method. Everything else seems very dangerous to me.

Answer 2

The "implied else" of the if (cell == nil) is that it's reusing a cell from the table's cache. It doesn't reset anything about those, it just picks them up and uses them. Which means that any element you've got on there needs to be cleared manually, especially if it's going to be some time before they're filled in.
You're already doing some defaulting, here:
if([urlLink length] ==0)
{
imageView.image=[UIImage imageNamed:#"ioffer.png"];
}
If you just make that NOT conditional -- ie just say
imageView.image=[UIImage imageNamed:#"ioffer.png"];
what you'll get is, your cell will load with its default image, then when the image loads remotely it'll replace it.
NOW: You're doing that image load synchronously. Which means your whole UI is going to freeze while the web request is being made. Not great.

Answer 3

I had the same issue. The cells are reused at an other index, when scrolling.
Try putting the code, that fills the cells with data, outside the "if (cell == nil)". Worked for me.
Best regards,
Alexander

Answer 4

You also use the custom cell instead of this and check each time
as like given below example-
Condition-
if(shout.creator.avatarImage){
avatarView.image = shout.creator.avatarImage;
}
else{
FetchImageOperation *operation = [[FetchImageOperation alloc] init];
operation.delegate = self;
operation.urlString = shout.creator.avatarURL;
[operationQueue addOperation:operation];
[operation release];
}
-(void)fetchthumbImageOperation:(FetchThumbImageOperation *)operation didFetchImage:(UIImage *)image
{
avatarView.image= image;
}
Here, i check the condition for image in tableview data source.
-(UITableViewCell *)tableView:(UITableView *)tv cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
}