Image lazy loading in table view - iphone

Question

I want to use lazy loading of images concept in my table view. My array of image rul string is ( MSMutableArray ) "images". How can I implement this in cellForRowAtIndexPath.
It looks like:
-(UITableViewCell *) tableView:(UITableView *)AtableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
UITableViewCell *cell=[searchtable dequeueReusableCellWithIdentifier:#"cell"];
if(!cell)
{
cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:#"cell"];
cell.textLabel.font=[UIFont systemFontOfSize:12];
cell.imageView.image=[UIImage imageWithData:[NSData dataWithContentsOfURL:[NSURL URLWithString:[appSmallLogos objectAtIndex:indexPath.row]]]];
cell.detailTextLabel.text=[appReleaseDates objectAtIndex:indexPath.row];
}
return cell;
}

Answer 1

Try this code :
UIActivityIndicatorView *indicator = [[UIActivityIndicatorView alloc]initWithActivityIndicatorStyle:UIActivityIndicatorViewStyleWhiteLarge];
indicator.frame = CGRectMake(your bounds);
[cell addSubview:indicator];
[indicator bringSubviewToFront:self.view];
[indicator startAnimating];
dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0ul);
dispatch_async(queue, ^{
//This is what you will load lazily
NSString *u=[NSString stringWithContentsOfFile:r.url encoding:NSUTF8StringEncoding error:nil];
NSURL *imageURL=url;
NSData *image=[NSData dataWithContentsOfURL:imageURL];
dispatch_sync(dispatch_get_main_queue(), ^{
CustomCell *cell = (CustomCell *)[tableView cellForRowAtIndexPath:indexPath];
cell.imageView.image=[UIImage imageWithData:image];
[cell setNeedsLayout];
[indicator stopAnimating];
});
});
cell.cellDescription.text=r.url;// this is which you want to add in first time.
I am not sure but try it.

Answer 2

You can use the SDWebImage library, the library will download and cache the image asynchronously. by passing the url to it as argument
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *MyIdentifier = #"MyIdentifier";
UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:MyIdentifier];
if (cell == nil)
{
cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault
reuseIdentifier:MyIdentifier] autorelease];
}
// Here we use the new provided setImageWithURL: method to load the web image
[cell.imageView setImageWithURL:[NSURL URLWithString:#"http://www.domain.com/path/to/image.jpg"]
placeholderImage:[UIImage imageNamed:#"placeholder.png"]];
cell.textLabel.text = #"My Text";
return cell;
}

Answer 3

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
static NSString *CellIdentifier = #"Cell";
TableCellLayout *cell = (TableCellLayout *)[tableView dequeueReusableCellWithIdentifier:CellIdentifier];
if(cell == nil)
{
cell = [[TableCellLayout alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
}
cell.cellName = [[array valueForKey:#"name"] objectAtIndex:indexPath.row];
cell.cellImage = [UIImage imageNamed:#"placeholder.png"]; // add a placeholder
NSString *imageURL = [[array valueForKey:#"imageLink"] objectAtIndex:indexPath.row];
NSURL *theURL = [NSURL URLWithString:imageURL];
if (asynchronousImageLoader == nil){
asynchronousImageLoader = [[AsynchronousImages alloc] init];
}
[asynchronousImageLoader loadImageFromURL:theURL];
cell.cellImage = asynchronousImageLoader.image;
return cell;
}
I finally managed to do it setting the image with:
– performSelectorOnMainThread:withObject:waitUntilDone:
After the image is downloaded