title: UIbutton not responding to touch
body: <p>I have this view hierarchy:
  <img src="https://i.stack.imgur.com/iIJEP.png" alt="enter image description here"></p>
  
  <p>The three buttons don't response. They are enabled, just when I touch there, they don't do anything (not even change their gradient/tint) which tells me they are not even received the touches. Is there something I am doing wrong?
  Thanks</p>
  
  <p>User interaction is enabled on all the buttons' superviews, and the buttons themselves. The buttons are also enabled.</p>