title: Twitter OAuth iPhone problem
body: <p>I'm adding a twitter module on my program for both iPhone and iPad.
  And I have met two problems.</p>
  
  <hr>
  
  <p>1st, on iPhone.
  After I merged my twitter module to my iPhone program, <strong>build fails only in Debug mode.</strong> It's ok in Release mode.</p>
  
  <p>The error message is simply </p>
  
  <pre><code>Libxml/xmlreader.h: No such file or directory
  </code></pre>
  
  <p>Yes, it is because gcc can't locate it.
  But I have added <code>-lxml2</code> for Other Linker Flags, and <code>/usr/include/libxml2/**</code> for Header Search Paths in project build settings on Release and Debug mode both.</p>
  
  <hr>
  
  <p>2nd, on iPad.
  After I merged twitter module to iPad program, build fails with the message below.</p>
  
  <pre><code>ld: duplicate symbol _OBJC_METACLASS_$_MGTwitterEngine in 
  /Users/eddy/Documents/iOS/workspace/.../i386/MGTwitterEngine-3460BD6C4381A3AC.o and  
  /Users/eddy/Documents/iOS/workspace/.../i386/MGTwitterEngine-CC42501E82512F61.o
  
  Command /Developer/Platforms/iPhoneSimulator.platform/Developer/usr/bin/gcc-4.2 
  failed with exit code 1
  </code></pre>
  
  <p>I can't figure out the reason why this message comes.
  Is the readymade module only for iPhone?
  Or how can I fix it?</p>