gistfile1.txt

-(void) reloadTableCellsAtIndexPaths:(NSArray *) indexPaths {
    NSArray *visibleTableCells = [self.tableView indexPathsForVisibleRows];
    [indexPaths enumerateObjectsWithOptions:NSEnumerationConcurrent usingBlock:^(id obj, NSUInteger idx, BOOL *stop){
        BOOL isVisible = [visibleTableCells containsObject:obj];
        if (isVisible) {
            [self.tableView reloadRowsAtIndexPaths:[NSArray arrayWithObject:obj] withRowAnimation:UITableViewRowAnimationFade];
        }
    }];
   
}
 
#pragma mark - PBDownloadImageOperation delegates
 
-(void) imageDownloadOperation:(PBImageDownloadOperation *) imageDownloadOperation didDownloadImageData:(NSData *) imageData {
    // Cache the image.
    [imageCache cacheObject:imageData forKey:imageDownloadOperation.imageURL];
   
    [self performSelectorOnMainThread:@selector(reloadTableCellsAtIndexPaths:) withObject:[NSArray arrayWithObject:imageDownloadOperation.imageIndexPath] waitUntilDone:NO];
}
 
-(void) imageDownloadOperation:(PBImageDownloadOperation *)imageDownloadOperation didFailWithError:(NSError *) error {
    // Display error and/or optionally retry the image downloading...
}