title: iOS Facebook SDK Linking with Unity on Simulator Issue
body: <p>Currently getting the following when trying to link for the simulator, works fine on hardware.  Using the latest Facebook SDK.</p>
  
  <pre><code>Undefined symbols for architecture i386:
   "_UnityGetGLViewController", referenced from:
    _FBNativeAdClick in FBAudienceNetwork(FBNativeAdCBridge.o)
  ld: symbol(s) not found for architecture i386
  </code></pre>
  
  <p>Anyone else have seen this?</p>
  
  <p>FB_AD_SDK_VERSION @"3.21.1"</p>