title: tableView(_:heightForHeaderInSection:) not working
body: <p>I am implementing a <code>UITableView</code> within my <code>UIViewController</code>. I have been able to get my text to display with a custom <code>UITableViewCell</code>, but I can not find a way to put spacing between my cells.</p>
  
  <p>I have tried implementing <code>tableView(_:heightForHeaderInSection:)</code>, but it seems that it is not called as I have tried to put in a print statement to see if it runs.</p>