title: Xcode shows many errors but program compiles and runs fine (in both simulator and device)
body: <p>After installing the CocoaLumberjack' log compressor class I've been getting this annoying behavior: Xcode complains that there are many undeclared identifiers and gives me many errors (not warnings but errors with the red icon). </p>
  
  <p>The thing is that I can compile and run my iPad app just fine but Xcode won't do any autocompletion. I tried cleaning the build folder (Product > <kbd>option</kbd> + Clean), and also deleting derived data. I've also rebooted to no avail. </p>
  
  <p>As you can imagine this is a pain to work with. I did have this behavior happen before on a previous version of Xcode; it had something to do with stuff in my precompiled headers file but using the solution above would always fix it. I'm currently using Xcode 4.4 (4F250).</p>
  
  <p>Sample error I'm getting:</p>
  
  <p><code>Semantic Error: use of undeclared identifier 'DDTTYLogger'</code></p>
  
  <p>The above happens even with classes that I wrote myself and that have <em>not changed</em> since installing the CocoaLumberjack compressor class.</p>