title: Scroll UITableView up before popping UIViewController
body: <p>I have a custom pop transition and it depends on the <code>UITableView</code> being scrolled to the top before performing the transition. The second I tap the back button of my <code>UIViewController</code> I want to scroll the <code>UITableView</code> up which will then have the correct state for my transition.</p>
  
  <p>I already tried to scroll the <code>UITableView</code> up before the view will get dismissed:</p>
  
  <pre><code>override func viewWillDisappear(_ animated: Bool) {
      super.viewWillDisappear(animated)
      self.tableView.scrollToRow(at: IndexPath(row: 0, section: 0), at: .top, animated: false)
  }
  </code></pre>
  
  <p>This however failed to scroll at all. How can I move the <code>UITableView</code> to the top before the <code>UIViewController</code> gets dismissed?</p>