title: Undefined symbols for architecture armv7, ld: symbol(s) not found for architecture armv7
body: <p>I am implementing google cloud messaging in my project, and i have setup cocoapods in my project. But when I run the project it generate error, this error is 
  <strong>Undefined symbols for architecture armv7:
    "_OBJC_CLASS_$_SKProductsRequest", referenced from:
        objc-class-ref in libGGLCore.a(GMRProductsRequest.o)
    "_OBJC_CLASS_$_SKPaymentQueue", referenced from:
        objc-class-ref in libGGLCore.a(GMRInAppPurchaseTransactionReporter.o)
  ld: symbol(s) not found for architecture armv7
  clang: error: linker command failed with exit code 1 (use -v to see invocation)</strong>. I am using Xcode 7 and swift 2 and my pod version is 1.0.0.beta.2</p>
  
  <p>Please help me, I am not able to solve this issue.</p>