title: Why is the interface builder action for tap gesture recognizer in iOS not fire?
body: <p>In iOS in Xcode, I dropped a tap gesture recognizer control onto a label, and control-dragged the tap gesture recognizer to create an interface builder action. When I tap the label, the interface builder action doesn't fire. Here is my code:</p>
  
  <pre><code>@IBAction func actionTapLabelInstrumentDropDown(_ sender: UITapGestureRecognizer) {
  
      print("actionTapLabelInstrumentDropDown")
  
      instrumentDropDown.show()
  
  }
  </code></pre>
  
  <p>The print statement never prints.</p>