title: What does the term 'session' mean in layman terms for the editingDidBegin property of the UIControlEvent object?
body: <p>While following a tutorial, I prejudged the next step of the tutorial and decided to try it on my own.  The objective is to connect an IBAction function to a touch event so that once we begin editing a UITextField then it will update a UILabel.  I jumped ahead of the tutorial that suggests connecting to the 'Editing Changed' option in the connections inspector, but I unknowingly made a connection to the 'Editing Did Begin' because it made sense verbally.  </p>
  
  <p>I ran the application and my UILabel wasn't updating.  Therefore I re-read the tutorial slowly and noticed that I needed to use the 'Editing Changed' touch event instead.  I wanted to understand why it didn't work initially so after checking Apple's reference material on <a href="https://developer.apple.com/documentation/uikit/uicontrolevents" rel="nofollow noreferrer">UIControlEvents</a>, I noticed that it uses the terms 'editing session'.  Can anyone explain what a session is?  </p>
  
  <p>Hopefully this way I'll understand why my process didn't work on the first try.</p>
  
  <p><a href="https://i.stack.imgur.com/rl4o7.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/rl4o7.png" alt="enter image description here"></a></p>
  
  <pre><code>class ConversionViewController: UIViewController {
      @IBOutlet var celsiusLabel: UILabel!
      @IBAction func fahrenheitFieldEditingChanged(textField: UITextField){
          celsiusLabel.text = textField.text
      }
  }
  </code></pre>
  
  <p>Thank you in advance</p>