- (void)perform {
    // Get a hold of the controllers
    UIViewController *toController = self.destinationViewController;
    UIViewController *fromController = self.sourceViewController;
    UIViewController *containerController = fromController.parentViewController;
    // Get hold of the views
    UIView *toView = toController.view;
    UIView *fromView = fromController.view;
    UIView *containerView = fromView.superview;
    // Tell both controllers that the transition is begining
    [toController beginAppearanceTransition:YES animated:YES];
    [fromController beginAppearanceTransition:NO animated:YES];
    // Add the controller as a child controller
    [containerController addChildViewController:toController];
    // Make sure that the to view is in the correct position
    toView.frame = fromView.frame;
    // Add the new view to the back of the container view
    [containerView insertSubview:toView belowSubview:fromView];
    // Animate the old view down
    [UIView animateWithDuration:0.35
                          delay:0.0
                        options:UIViewAnimationOptionCurveEaseInOut
                     animations:^{
                         CGRect frame = fromView.frame;
                         frame.origin.y = containerView.bounds.size.height;
                         fromView.frame = frame;
                     }
                     completion:^(BOOL finished) {
                         // Tell the new controller that it has moved
                         [toController didMoveToParentViewController:containerController];
                         // Remove the old view and controller
                         [fromController willMoveToParentViewController:nil];
                         [fromView removeFromSuperview];
                         [fromController removeFromParentViewController];
                         // Tell the controllers that the transition has finished
                         [toController endAppearanceTransition];
                         [fromController endAppearanceTransition];
                     }];
}