title: Parse.com - Undefined symbols for architecture x86_64
body: <p>I've updated my project to use the new Parse Framework(1.6.2) and the log shows an problem with the architecture x86_64.
  I'm using Standart Arch(armv7,arm64) and the FacebookSDK (w/ -ObjC flag).
  Anyone knows how to solve that? </p>
  
  <pre><code>Undefined symbols for architecture x86_64:
    "_OBJC_CLASS_$_BFExecutor", referenced from:
        objc-class-ref in Parse(PFObject.o)
        objc-class-ref in Parse(PF_Twitter.o)
        objc-class-ref in Parse(PFPush.o)
        objc-class-ref in Parse(PFEventuallyQueue.o)
        objc-class-ref in Parse(PFPinningEventuallyQueue.o)
        objc-class-ref in Parse(PFCloud.o)
        objc-class-ref in Parse(PFUser.o)
        ...
    "_OBJC_CLASS_$_BFTask", referenced from:
        objc-class-ref in Parse(PFSQLiteDatabase.o)
        objc-class-ref in Parse(PFTwitterAuthenticationProvider.o)
        objc-class-ref in Parse(PFObjectEncodingStrategy.o)
        objc-class-ref in Parse(PFOfflineStore.o)
        objc-class-ref in Parse(PFObject.o)
        objc-class-ref in Parse(PF_Twitter.o)
        objc-class-ref in Parse(PFAnonymousAuthenticationProvider.o)
        ...
    "_OBJC_CLASS_$_BFTaskCompletionSource", referenced from:
        objc-class-ref in ParseFacebookUtils(PFFacebookAuthenticationProvider.o)
        objc-class-ref in Parse(PFSQLiteDatabase.o)
        objc-class-ref in Parse(PFOfflineStore.o)
        objc-class-ref in Parse(PFObject.o)
        objc-class-ref in Parse(PF_Twitter.o)
        objc-class-ref in Parse(PFNetworkCommandRunner.o)
        objc-class-ref in Parse(PFEventuallyQueue.o)
        ...
  ld: symbol(s) not found for architecture x86_64
  clang: error: linker command failed with exit code 1 (use -v to see invocation)
  </code></pre>