Want to show UIActivityIndicator on UITableViewCell while setting images on UITableViewCell - iphone

Question

I have a table with horizontal and vertical scrolling in UITableView,and each cell has a UIImageView and i am setting image on cell's UIImageView by URL.I want to show the ActivityIndicator on all cells until the images is downloaded.I have search a lot but didn't find anything good.
Here is my code for CellForRowAtIndexPath
static NSString *CellIdentifier = #"ArticleCell";
NSDictionary *dict=[self.articles objectAtIndex:indexPath.row];
__block ArticleCell_iPhone *cell = (ArticleCell_iPhone *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
//added for uiacticvaty indicator on uitableviewcell
UIActivityIndicatorView *loadingActivity = [[UIActivityIndicatorView alloc]
initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhite];
[loadingActivity startAnimating];
loadingActivity.frame = cell.thumbnail.frame;
loadingActivity.frame = CGRectMake(0, 0, 90 , 90);
[loadingActivity setBackgroundColor:[UIColor greenColor]];
UIView* parent = [cell.thumbnail superview];
[parent addSubview:loadingActivity];
[parent bringSubviewToFront:loadingActivity];
//
//added for uiacticvaty indicator
if (cell == nil)
{
cell=[[[ArticleCell_iPhone alloc]initWithFrame:CGRectMake(0, 0, kCellWidth_iPad, kCellHeight_iPad) withNSDict:dict] autorelease];
__block NSDictionary *currentArticle = [self.articles objectAtIndex:indexPath.row];
dispatch_queue_t concurrentQueue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dispatch_async(concurrentQueue, ^{
UIImage *image = [UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:[currentArticle objectForKey:#"thumbnail_url"]]]];
dispatch_async(dispatch_get_main_queue(), ^{
[cell.thumbnail setImage:image];
// [loadingActivity stopAnimating];
cell.titleLabel.text = [currentArticle objectForKey:#"Title"];
});
});
}
// [cell.imagefooter setImage:[UIImage imageNamed:#"line"]];
return cell;
}

Answer 1

Consider leveraging open source solutions like SDWebImage (with UIActivityIndicator-for-SDWebImage).

Answer 2

It´s necessary to have a "background" to the cell.imageView... But must be a image, not just a frame. So just create a UIImage as a "white background" and set in cell.imageView.image. The code will be:
UIActivityIndicatorView *spinner = [[UIActivityIndicatorView alloc]
initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleGray];
UIImage *whiteback = [[UIImage alloc] initWithContentsOfFile:#"whiteback.png"];
cell.imageView.image = whiteback;
[cell.imageView addSubview:spinner];
[spinner startAnimating];
cell.textLabel.text=#"Carregando...";
[whiteback release];
[spinner release];
The whiteback.png is just a 25x25 pixels white square...
Thanks

Answer 3

Give tag to your activity indicator using custom cell.
UITableViewCell *aCell=[tableView dequeueReusableCellWithIdentifier:#"MyIdentifier"];
UIActivityIndicatorView *aActivity=(UIActivityIndicatorView *)[aCell viewWithTag:1];
[aActivity startAnimating];
return aCell;
I tried this code in my demo and its working perfectly.