I'm using Grand Central Dispatch to load images of a UITableViewCell asynchronously. This works well except in some border cases in which the cell is reused, and a previous block loads the wrong image.
My current code looks like this:
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
static NSString *CellIdentifier = @"Cell";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if (!cell) {
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
}
NSString *imagePath = [self imagePathForIndexPath:indexPath];
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0ul);
dispatch_async(queue, ^{
UIImage *image = [UIImage imageWithContentsOfFile:imagePath];
dispatch_sync(dispatch_get_main_queue(), ^{
cell.imageView.image = image;
[cell setNeedsLayout];
});
});
return cell;
}
As far as I know GCD queues cannot be stopped. How can this border case be prevented then? Or should I be using something else instead of GCD to solve this problem?