title: addSubview not working
body: <pre><code>// Create and add a sub view
  CGRect viewRect = CGRectMake(0, 0, 200, 200);
  UIView *a_sub_view = [[UIView alloc] initWithFrame : viewRect];
  
  [window addSubview : a_sub_view];
  </code></pre>
  
  <p>After adding the above 3 lines of code, xcode produces no errors or warnings.  But the sub-view is not showing at all.  The sample program seems to be running exactly as before.  Hope that somebody knowledgable could help.</p>