flipping UIViews ???

Question

i am using the following code to flip between two UIViews..

- (IBAction)switchView:(id)sender
{

UIView *mainView =View1.view;
UIView *flipsideView =View2.view;

[UIView beginAnimations:@"View" context:nil]; 
[UIView setAnimationDuration:1.00]; 

[UIView setAnimationTransition: UIViewAnimationTransitionCurlUp forView:self.view cache:YES];

if([mainView superview] !=nil)
{

    [View2 viewWillAppear:YES];
    [View1 viewWillDisappear:YES];
    [mainView removeFromSuperview];

    [self.view addSubview:flipsideView];

}
else
{
    [View1 viewWillAppear:YES];
    [View2 viewWillDisappear:YES];
    [flipsideView removeFromSuperview];

    [self.view addSubview:mainView];

}
[UIView commitAnimations];  
}

View2 is a different xib file but still when i use the code same View1 appears after flipping..what am i doing wrong in here??