title: How does UIScrollView steal touches from its subviews?
body: <p>I'd like to be able to create my own container subclasses of UIView which can react first to touches, before their subviews.  This is tricky because normally a subview receives touch events (via <code>touchesBegan:</code> etc) before superviews.  How does UIScrollView reverse this?</p>
  
  <p>To be clear, I am <em>not</em> asking how UIScrollView <em>behaves</em>.  I understand what it does, and how you would normally use it.  I'm asking about how I could cleanly implement my own version of this -- not because I want to, but because I'm trying to build reusable container views that take advantage of similar behavior.</p>