title: Transparent view on another transparent UIView with non-transparent content?
body: <p>The idea is to show a progress dialog. 
  I'm trying to cover a parent view (normally the whole screen) with a transparent black view (alpha 0.2). On top of that I want to show a smaller view, also transparent with another color. It may be not influenced by color or transparency of the first view. 
  In that 2nd view I want UI elements that are opaque. 
  I have tried everything and even found posts here that deal with something similar but only uses one transparent layer. And those already use weird tricks. 
  Is there a standard, easy way of achieving this?</p>