if ([FBSDKAccessToken currentAccessToken]) {
   [[[FBSDKGraphRequest alloc] initWithGraphPath:@"me" parameters:nil]
    startWithCompletionHandler:^(FBSDKGraphRequestConnection *connection, id result, NSError *error) {
      if (!error) {
         NSLog(@"fetched user:%@", result);
      }
  }];
}