Flip navigation controller

[UIView beginAnimations:nil context:NULL];
[UIView setAnimationDuration: 1];
[UIView setAnimationTransition:UIViewAnimationTransitionFlipFromRight forView:self.navigationController.view cache:YES];
[self.navigationController pushViewController:atab animated:YES];
//[self.navigationController pushViewController:myViewController animated:NO];
[UIView commitAnimations];