Using visibleCells to reference a cells image

Question

I am trying to set the image a cell
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
NSArray *visibleCells = [tableView visibleCells];
int i;
for (i=0; i<visibleCells count; i++) {
UITableViewCell *currentCell = [visibleCells objectAtIndex:i];
if (!currentCell.image) {
NSLog(@"loader setting image in cell: %d to URL: %@",currentCell.tag, [imgarr objectAtIndex:currentcell.tag]);
NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:[imgarr objectAtIndex:currentCell.tag]]];
if (data) {
cell.image = [[UIImage alloc] initWithData:data];
[currentCell setNeedsLayout];
how do the cells in visibleCells correlate to the cells in the tableView? I have an imgarr Array that holds the url to the image indexed to the same order as the cells in the table. cell.tag does not seem to work. I am setting the cell tag to "indexPath.row" during cell creation/setup, then trying to pass it as the objectAtIndex in the array. I simplified the code for the post i am actually queuing an operation to load the images in scrollViewDidEndDecelerating. I am getting the wrong images loaded to the cell. I hope my code is explanatory enough i had to cut out a lot of commented out tests.
Message was edited by: xnakx

Answer 1

if (cell == nil)
// no cell to reuse. so let's create a new one
cell = [[[UITableViewCell alloc] initWithFrame:CGRectZero reuseIdentifier:MyIdentifier] autorelease];
CGRect cellRectangle = CGRectMake(resTEXT_OFFSET, (resROW_HEIGHT - resLABEL_HEIGHT) / 2.0, resTEXT_WIDTH, resLABEL_HEIGHT);
label = [[UILabel alloc] initWithFrame:cellRectangle];
label.numberOfLines = 3;
label.tag =resTEXT_TAG;
label.font = [UIFont systemFontOfSize:12];
label.textColor = [UIColor colorWithRed:0.55 green:0.45 blue:0.36 alpha:1.0];
[cell.contentView addSubview:label];
[label release];
cell.selectionStyle = UITableViewCellSelectionStyleGray;
cell.textColor = [UIColor colorWithWhite:0.5 alpha:0.5];
cell.accessoryType = UITableViewCellAccessoryDisclosureIndicator;
cell.tag = indexPath.row;
} else {
//reuse the cell
cell.tag = indexPath.row;
label = (UILabel*)[cell.contentView viewWithTag:resTEXT_TAG];
then this gets called when the table is scrolled (it is actually queued as a NSOperation)
- (void)loadImagesOfVisibleCellsInTableView:(UITableView *)tableView {
[UIApplication sharedApplication].networkActivityIndicatorVisible = YES;
NSArray *visibleCells = [tableView visibleCells];
int i;
for (i=0; i<[visibleCells count]; i++) {
NSLog(@"visible Cell: %d",[visibleCells objectAtIndex:i]);
UITableViewCell *currentCell = [visibleCells objectAtIndex:i];
if (!currentCell.image) {
NSLog(@"loader setting image for cell: %d using url: %@",currentCell.tag, [imgarr objectAtIndex:currentCell.tag]);
NSData *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:[imgarr objectAtIndex:currentCell.tag]]];
if (data) {
currentCell.image = [[UIImage alloc] initWithData:data];
[currentCell setNeedsLayout];
[UIApplication sharedApplication].networkActivityIndicatorVisible = NO;
I can verify that the imgarr Array is indexed properly. Images get loaded but usually the wrong ones. It seems to be the same 9 or so images get loaded for the cells, All cells. not just the ones currently in visible.
ie. the table loads with no images at all (i have not set them for the initial cells for testing).
after the first scroll has stopped the loadImagesOfVisibleCellsInTableView function downloads about nine but when i scroll again i see images for all cells, the loadImagesOfVisibleCellsInTableView was called again but i am checking if the cell.image was already set before downloading and setting them so it does nothing.