title: UITableViewCell with Checkmark not visible
body: <p>I've a problem with my UITableView inside PopoverController.
  When I touch cell, the didSelectRowAtIndexPath function is called, and the cell accessoryType is changed. Example simplified :</p>
  
  <pre><code>- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {
      UITableViewCell *cell = [self.listItems objectAtIndex:indexPath.row];
      cell.accessoryType = UITableViewCellAccessoryCheckmark;
      [self.tableView reloadData];
      [self.popoverController dismissPopoverAnimated:YES];
  }
  </code></pre>
  
  <p>It's working, the cell are checked, but it's not visible on my tableview : I can't see the blue checkmark. However, in touch state on the cell, the checkmark is visible in white (and the cell background is gray). But not visible in default state.</p>
  
  <p>Do you have any idea why my checkmark are not visible in default state ?</p>
  
  <p>Thanks,</p>
  
  <p>Edit: Add screenshot, for a cell with <code>accessoryType = UITableViewCellAccessoryCheckmark</code></p>
  
  <p><img src="https://i.stack.imgur.com/pIHS8.jpg" alt="enter image description here"></p>