ios – NSAttributedString冻结UITableView

- (void)setSubtitleForCell:(TTTableViewCell *)cell item:(TTPhotoPost *)item
{
    NSAttributedString *attributedString = [[NSAttributedString alloc] initWithData:
                                            [item.caption dataUsingEncoding:NSUnicodeStringEncoding]
                                                                            options:@{ NSDocumentTypeDocumentAttribute: NSHTMLTextDocumentType }
                                                                 documentAttributes:nil
                                                                              error:nil];

    [cell.descriptionLabel setAttributedText:attributedString];
}

那里有什么错误吗？或某种方式使att.String更快？