title: Command /Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang failed with exit code 1
body: <p>I'm trying to do an application reading pdf using pdf kit in Xcode 4.3 but it gives me the following error </p>
  
  <pre><code>ld: duplicate symbol _OBJC_METACLASS_$_OverlayManager in /Users/dt4it/Library/Developer/Xcode/DerivedData/MyPdf4-bmkjglhhvneluqcbwpceiqjvdcmq/Build/Intermediates/MyPdf4.build/Debug-iphonesimulator/MyPdf4.build/Objects-normal/i386/OverlayManager-D0866CFD31A05E68.o and /Users/dt4it/Library/Developer/Xcode/DerivedData/MyPdf4-bmkjglhhvneluqcbwpceiqjvdcmq/Build/Intermediates/MyPdf4.build/Debug-iphonesimulator/MyPdf4.build/Objects-normal/i386/OverlayManager-B31AE7412100AF6D.o for architecture i386
  Command /Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang failed with exit code 1
  </code></pre>
  
  <p>any help please ??</p>