title: "no symbol XXX in current context" for specific classes in debugging of XCode ip* project
body: <p>I randomly get this error, and I can't figure out a way to fix it: the variables pane (top right) is blank, and the gdb "po" command can't print any variables.</p>
  
  <p><img src="https://i.stack.imgur.com/2deZ7.png" alt="Debugger with no variables"></p>
  
  <p>The "po" command doesn't even know about "self":
  <img src="https://i.stack.imgur.com/P93hs.png" alt="No po either."></p>
  
  <p>The problem appears specifically for <em>all</em> methods in the <code>MGMinimap</code> class. Nowhere else. I can debug from A and see <code>self</code> and the others, and then as soon as A steps into <code>MGMinimap</code>, the variables pane goes blank like the above image, and gdb doesn't work at all. </p>
  
  <p>The temporary solution to this problem is to create a new class in XCode called e.g. <code>MGMinimapNew</code>, copy-paste everything from the real class's .h and .m into the new class, renaming the old class files to e.g. <code>MGMinimapOld.m|h</code>, then renaming the new class to <code>MGMinimap.m|h</code>. Doing this, things start working again. Still looking for a <em>real</em> answer though.</p>
  
  <p><strong>Update</strong> in answer to <strong>Rob Napier:</strong></p>
  
  <ul>
  <li>Run>Sync with Debugger. I always have high hopes for this. Occasionally it even works.
  
  <ul>
  <li>Unfortunately this wasn't one of those occasions :)</li>
  </ul></li>
  <li>Select a different stack frame, then select this stack frame again.
  
  <ul>
  <li>No change</li>
  </ul></li>
  <li>Switch threads and switch back.
  
  <ul>
  <li>No change</li>
  </ul></li>
  <li>Step-over. Often going to the next line will sync things back up.
  
  <ul>
  <li>No change</li>
  </ul></li>
  </ul>