title: Get section number in custom cell button action
body: <p>I have a tableView dynamically populated with custom cells in several sections. </p>
  
  <p>In my CustomCell class I have an @IBAction for a custom checkbox button in the cell. Is there a way to get the section number of the sender button in the IBAction function?</p>
  
  <p>Something like:</p>
  
  <pre><code>@IBAction func checkboxButton(sender: CheckBox) {
      //Change Button state
      if sender.isChecked == true { sender.isChecked = false }
      else { sender.isChecked = true }
  
      //Get section number of clicked button
      var sectionNumber = ???????
  
  }
  </code></pre>