objective-c - Suggestions on asynchronous image loading for UITableView in iOS

Question

I am currently loading my table with a left-sided thumbnail, title and subtitle using this code:

- (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];
    }

    NSDictionary *post           = [posts objectAtIndex:indexPath.row];

    cell.textLabel.text       = [post objectForKey:@"post_text"];
    cell.detailTextLabel.text = [post objectForKey:@"post_author_name"];

    NSString *postpictureUrl = [post objectForKey:@"picture"];
    NSData   *data           = [NSData dataWithContentsOfURL:[NSURL URLWithString:postpictureUrl]];

    cell.imageView.image = [UIImage imageWithData:data];

    return cell;
}

Of course this will not work in production due to the synchronous loading I am doing here.

What is your suggestion for asynchronous loading of images in a situation like this?

I've found AF Networking (haven't used it yet) but wonder if there's a more lightweight approach to this issue.

Answer 1

AsyncImageView is your friend, check it out here.

Just set the imageURL and you are good to go.

Answer 2

Use lazy loading in table view
Use this code


    (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];
        }

        NSDictionary *post = [posts objectAtIndex:indexPath.row];

        cell.textLabel.text = [post objectForKey:@"post_text"];
        cell.detailTextLabel.text = [post objectForKey:@"post_author_name"];
    dispatch_queue_t queue = dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH,  0ul);
        dispatch_async(queue, ^{
         //This is what you will load lazily
      NSString *postpictureUrl = [post objectForKey:@"picture"];
        NSData   *data = [NSData dataWithContentsOfURL:[NSURL URLWithString:postpictureUrl]];
            dispatch_sync(dispatch_get_main_queue(), ^{

        cell.imageView.image = [UIImage imageWithData:data];
                [cell setNeedsLayout];
      }); 
}); 

        return cell;
    }