- (IBAction)switchViews:(id)sender
{
    UIViewAnimationTransition transition;
    UIViewController* switchTo;

    if (self.yellowViewController.view.superview == nil)
    {
        if (self.yellowViewController == nil)
        {
            self.yellowViewController = loadYellowViewController();
        }

        transition = UIViewAnimationTransitionFlipFromRight;
        switchTo = self.yellowViewController;
    }
    else
    {
        if (self.blueViewController == nil)
        {
            self.blueViewController = loadBlueViewController();
        }

        transition = UIViewAnimationTransitionFlipFromLeft;
        switchTo = self.blueViewController;
    }

    [UIView animateWithDuration:1.25
                          delay:0.0
                        options:UIViewAnimationCurveEaseInOut
                     animations:^{
                         [UIView setAnimationTransition:transition forView:self.view cache:YES];
                         [self switchToViewController:switchTo];
                     }
                     completion:nil
     ];
}