AFNetworking fade in on first load only.

gistfile1.m

  __weak UITableViewCell *weakCell = cell;  
  [cell.imageView setImageWithURLRequest:[NSURLRequest requestWithURL:[NSURL URLWithString:url]]
                        placeholderImage:nil
                                 success:^(NSURLRequest *request, NSHTTPURLResponse *response, UIImage *image) {
                                       if (response.statusCode == 0) return;
                                       weakCell.imageView.alpha = 0;
                                       weakCell.imageView.image = image;
                                       [UIView animateWithDuration:0.5
                                                             delay:0
                                                           options:UIViewAnimationCurveEaseIn
                                                        animations:^{
                                                            weakCell.imageView.alpha = 1;
                                                        }
                                                        completion:nil];
                                } failure:^(NSURLRequest *request, NSHTTPURLResponse *response, NSError *error) {}];