title: "self" not available in debugger on iOS 5.1
body: <p>I'm trying to debug a problem running under iOS 5.1 and when I stop in the debugger inside the code that gets the error and try to print something with the debugger I get the message:</p>
  
  <blockquote>
    <p>error: warning: Stopped in a context claiming to capture an
    Objective-C object pointer, but 'self' isn't available; pretending we
    are in a generic context</p>
  </blockquote>
  
  <p>Excuse me?  Does anybody know what I've done to myself here?</p>
  
  <p>The code is way too complicated for anybody to want to look it -- I'm mostly hoping somebody can tell me what the debugger message means.</p>
  
  <p>This used to fail only intermittently but now fails mostly.  The operation generally (or maybe always) works the first time I try it in iOS 5.1, occasionally after the first time, and apparently always works in iOS 6.</p>
  
  <p>If it helps to know the general context ...
  I'm trying to add a just-written object to an ALAssetsGroup so this is in a completion block  on a non-UI thread.  I  have a sensible-looking stack backtrace for a completion block.
  The failure is because the stored ALAssetsGroup no longer has a meaningful value -- or so says an NSLog of it that knows that it is an ALAssetsGroup object.  This value is assigned in one place (and logged so I track that) and I can see the initial assignment with key-value observing and I don't see it ever being changed in a KVO-sorta way.</p>