title: Can't get rid of Apple LLVM 5.0 Error
body: <p>It keeps saying:</p>
  
  <blockquote>
    <p>fatal error: file '/Applications/Xcode5-DP5.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS7.0.sdk/usr/include/objc/NSObject.h' </p>
    
    <p>has been modified since the precompiled header </p>
    
    <p>'/Users/jackiexu/Library/Developer/Xcode/DerivedData/ModuleCache/2MWVPCGUMQ29P/ObjectiveC.pcm' was built</p>
    
    <p>note: after modifying system headers, please delete the module cache at '/Users/jackiexu/Library/Developer/Xcode/DerivedData/ModuleCache/2MWVPCGUMQ29P'</p>
    
    <p>1 error generated.</p>
  </blockquote>
  
  <p>I must have deleted the derived data at least five times by now, and I'm getting nowhere. Any ideas?</p>