title: Undefined symbols for architecture arm64. While using static library
body: <p>I'm building a demo project which uses a 3d engine names "OpenSceneGraph" writing in C++, this engine provides tens of .a static library files after building. while I use those .a files in my xcode project, errors appeared</p>
  
  <pre><code>Undefined symbols for architecture arm64:
  referenced from: in xxx.a    
  ld: symbol(s) not found for architecture arm64
  </code></pre>
  
  <p>I checked those .a files by using "lipo -info" command, they all support arm64 architecture. I got confused now. </p>