title: Getting "_OBJC_CLASS_$_NgnEngine" error after linking iOS fat library
body: <p>Why i am still getting this error even after linking fat library</p>
  
  <pre><code>Undefined symbols for architecture i386:
    "_OBJC_CLASS_$_NgnEngine", referenced from:
        objc-class-ref in ViewController.o
  ld: symbol(s) not found for architecture i386
  clang: error: linker command failed with exit code 1 (use -v to see invocation)
  </code></pre>
  
  <p>and linking everything in "User-Defined</p>
  
  <p><img src="https://i.stack.imgur.com/8hzKK.png" alt="enter image description here"></p>
  
  <p><img src="https://i.stack.imgur.com/I1cho.png" alt="enter image description here"></p>
  
  <p><img src="https://i.stack.imgur.com/sDqai.png" alt="enter image description here"></p>
  
  <p><img src="https://i.stack.imgur.com/jZSOQ.png" alt="enter image description here"></p>
  
  <p>I am following the instruction which written here <a href="http://code.google.com/p/idoubs/wiki/Building_iDoubs_v2_x" rel="nofollow noreferrer">Link ios-ngn-stak to your app</a>
  any help please, this is tiring me and it is my senior project </p>