I do it that way to avoid memory leaks:
NSURL *url = [NSURL URLWithString:@"http:url..."];
NSURLRequest *request = [NSURLRequest requestWithURL:url];
UIImage *placeholderImage = [UIImage imageNamed:@"your_placeholder"];
__weak UITableViewCell *weakCell = cell;
[cell.imageView setImageWithURLRequest:request
placeholderImage:placeholderImage
success:^(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image) {
weakCell.imageView.image = image;
[weakCell setNeedsLayout];
} failure:nil];
It works fine with AFNetworking 2.
As @Greg suggest in a comment:
You have to add #import "UIImageView+AFNetworking.h".