google calendar API in iPhone app!

I just add gcal to my project according to this tutorial http://www.youtube.com/watch?v=it_9H0GxRNI but 12 errors is appeared:

"_SecItemAdd", referenced from:
          -[GDataOAuthKeychain setPassword:forService:account:error:] in GDataOAuthViewControllerTouch.o
      "_kSecMatchLimit", referenced from:
          _kSecMatchLimit$non_lazy_ptr in GDataOAuthViewControllerTouch.o
      "_kSecClassGenericPassword", referenced from:
          _kSecClassGenericPassword$non_lazy_ptr in GDataOAuthViewControllerTouch.o
      "_SecItemDelete", referenced from:
          -[GDataOAuthKeychain removePasswordForService:account:error:] in GDataOAuthViewControllerTouch.o
      "_kSecAttrGeneric", referenced from:
          _kSecAttrGeneric$non_lazy_ptr in GDataOAuthViewControllerTouch.o
      "_SecItemCopyMatching", referenced from:
          -[GDataOAuthKeychain passwordForService:account:error:] in GDataOAuthViewControllerTouch.o
  开发者_Python百科    "_kSecValueData", referenced from:
          _kSecValueData$non_lazy_ptr in GDataOAuthViewControllerTouch.o
      "_kSecReturnData", referenced from:
          _kSecReturnData$non_lazy_ptr in GDataOAuthViewControllerTouch.o
      "_kSecAttrAccount", referenced from:
          _kSecAttrAccount$non_lazy_ptr in GDataOAuthViewControllerTouch.o
      "_kSecClass", referenced from:
          _kSecClass$non_lazy_ptr in GDataOAuthViewControllerTouch.o
      "_kSecAttrService", referenced from:
          _kSecAttrService$non_lazy_ptr in GDataOAuthViewControllerTouch.o
      "_kSecMatchLimitOne", referenced from:
          _kSecMatchLimitOne$non_lazy_ptr in GDataOAuthViewControllerTouch.o
    ld: symbol(s) not found
    collect2: ld returned 1 exit status
Build failed (12 errors, 1 warning)

And no errors appears in console! what is the problem? :(

These symbols are defined in Security.framework so just add this to your project.