gistfile1.m

- (void) flipFromView:(UIViewController*)fromView toView:(UIViewController*)toView inDirection:(UIViewAnimationTransition)direction {
    [UIView beginAnimations:nil context:NULL];
    [UIView setAnimationDuration:1];
    [UIView setAnimationTransition:direction forView:[fromView view] cache:YES];

    [toView viewWillAppear:YES];
    [fromView viewWillDisappear:YES];
    
    [[fromView view] removeFromSuperview];
    [window addSubview:[toView view]];
    
    [toView viewDidAppear:YES];
    [fromView viewDidDisappear:YES];
    
    [UIView commitAnimations];
}