title: InsertRows to UITableView swift 4 has Error: My last row has scroll from top to bottom
body: <p>Here is my codes when expand section: </p>
  
  <pre><code>let lastScrollOffset = self.tableView.contentOffset
  self.tableView.beginUpdates()
  self.tableView.insertRows(at: indexPathsForSection(section: section), with: .none)//reloadSections([section], with: .fade)
  self.tableView.endUpdates()
  self.tableView.layer.removeAllAnimations()
  self.tableView.setContentOffset(lastScrollOffset, animated: false)
  let indexPath = IndexPath(row: NSNotFound, section: section)
  self.tableView.scrollToRow(at: indexPath, at: .none, animated: true)
  </code></pre>