title: Can't receive touch events from UIButtons placed ontop of GMSMapView
body: <p>I'm trying to place some static UI such as buttons on top of google maps. </p>
  
  <p>Currently for the screen I have</p>
  
  <p>UIView<br>
  &nbsp;&nbsp; - GMSMapView <br>
  &nbsp;&nbsp; - UIView <br>
  &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;- UIButton</p>
  
  <p>I changed the second UIView's layer.zPosition so that the view and button would show up, but I can't receive any touch events (touchupinside) from the UIButton.</p>