title: clang: error: linker command failed with exit code 1
body: <p>I just opened a project i havent worked for in a couple months, and just tried to compile and run it. </p>
  
  <p>I immediately got: </p>
  
  <pre><code>Undefined symbols for architecture i386:
   "l_OBJC_PROTOCOL_$_VideoOverviewControllerDelegate", referenced from:
      l_OBJC_CLASS_PROTOCOLS_$_FeaturedViewController in FeaturedViewController.o
    ld: symbol(s) not found for architecture i386
   clang: error: linker command failed with exit code 1 
  </code></pre>
  
  <p>and no amount of cleaning helped this error. I checked the two classes referenced in the error but couldn't find any error.</p>