title: admob ios7 error Audio framework
body: <p>I am integrating admob SDK (the current) in my last application IOS7-Xcode5 and i have a new error (same on new project), i guess i missed something, but i restarted the process many times and the error is still here: </p>
  
  <pre><code>Undefined symbols for architecture armv7:
    "_OBJC_CLASS_$_AVAudioSession", referenced from:
    objc-class-ref in libGoogleAdMobAds.a(GADDevice.o)
    "_AVAudioSessionPortHeadphones", referenced from:
        -[GADDevice audioRouteUsingAVAudioSession] in libGoogleAdMobAds.a(GADDevice.o)
    "_AVAudioSessionPortBuiltInSpeaker", referenced from:
        -[GADDevice audioRouteUsingAVAudioSession] in libGoogleAdMobAds.a(GADDevice.o)
  </code></pre>
  
  <p>I found how to resolve these errors in adding AudioUnit.framework but a new error appears framework not found AudioUnit... As my best friend Google tell me via stackoverflow, "don't use AudioUnit.framework, it's empty! Now use CoreAudio.framework." But my first error came back...</p>
  
  <p>If someone has the same problem and mainly a solution, i will be grateful :)</p>
  
  <p>PS: i tried -all_load and -ObjC, i linked AudioToolbox, i usually work with frameworks but also with careless mistakes ;) :/</p>