title: Can I create a totally transparent UIView that receives touches?
body: <p>I want to create a totally transparent UIView overlay (and it has subviews) to receives touches. I could set the alpha to a low value (like 0.02) to get an approximate effect. </p>
  
  <p>But I wonder is it possible for a <code>alpha == 0</code> UIView to receives touches, through other UIView configs?</p>