title: How to fix compile Mach-O Linker error
body: <p>I'm trying to add this iOS lib <a href="https://github.com/exalted/PTImageAlbumViewController" rel="nofollow">PTImageAlbumViewController</a> to an existing project that I'm working on and I'm getting compile errors. There is a sample project included and its dependent on a couple of other libs. The sample project works just fine but I can't get it migrated to my own project without errors.  I tried pulling the files direct from the project by dragging them from project to project but its still not working</p>
  
  <p>Is there something I'm missing?</p>
  
  <blockquote>
    <p>Undefined symbols for architecture armv7:
      "_OBJC_METACLASS_$_NetworkPhotoAlbumViewController", referenced from:
          _OBJC_METACLASS_$_PTImageAlbumViewController in PTImageAlbumViewController.o
      "_OBJC_CLASS_$_NIPhotoAlbumScrollView", referenced from:
          _OBJC_CLASS_$_PTImageAlbumView in PTImageAlbumView.o
      "_OBJC_CLASS_$_NetworkPhotoAlbumViewController", referenced from:
          _OBJC_CLASS_$_PTImageAlbumViewController in PTImageAlbumViewController.o
      "_NIPathForBundleResource", referenced from:
          -[PTImageAlbumViewController viewDidLoad] in PTImageAlbumViewController.o
      "_OBJC_METACLASS_$_NIPhotoAlbumScrollView", referenced from:
          _OBJC_METACLASS_$_PTImageAlbumView in PTImageAlbumView.o
    ld: symbol(s) not found for architecture armv7
    clang: error: linker command failed with exit code 1 (use -v to see invocation)</p>
  </blockquote>