title: How does one handle a text change event for a UITextField with Swift 4?
body: <p>From Objective C to later versions of swift, I have successfully used the <code>editingChanged</code> method to detect when text is changed in a <code>UITextField</code>. </p>
  
  <p>However it does not appear to work as of Swift 4. </p>
  
  <p>I have also tried the follow per several docs online:</p>
  
  <p><code>textField.addTarget(self, action: #selector(textFieldDidChange(_:)), for: UIControlEvents.editingChanged)</code></p>
  
  <p>And this also fails to hit the provided "@objc" function.</p>
  
  <p>There is now of course the <code>shouldChangeCharactersIn</code> delegate method but the limitation here is that this runs before, not after, a text change happens and means that any mutating can't happen until after it returns.</p>
  
  <p>Would appreciate any thoughts here, extremely frustrating that such trivial access to a core component is so elusive.</p>