Transition.m

- (void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext
{

    UIView *container = transitionContext.containerView;
    UIViewController *fromVC = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
    UIViewController *toVC = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];
    UIView *fromView = fromVC.view;
    UIView *toView = toVC.view;

    CGRect beginFrame = CGRectMake(UI_SCREEN_WIDTH, 0, UI_SCREEN_WIDTH, UI_SCREEN_HEIGHT);
    CGRect endFrame = CGRectMake(0, 0, UI_SCREEN_WIDTH, UI_SCREEN_HEIGHT);

    UIView *move = nil;
    if (toVC.isBeingPresented) {
        toView.frame = endFrame;
        move = [toView snapshotViewAfterScreenUpdates:YES];
        move.frame = beginFrame;
    } else {
        move = [fromView snapshotViewAfterScreenUpdates:YES];
        move.frame = fromView.frame;
        [fromView removeFromSuperview];
    }
    [container addSubview:move];

    [UIView animateWithDuration:TRANSITION_DURATION delay:0
         usingSpringWithDamping:100 initialSpringVelocity:1
                        options:0 animations:^{
                            move.frame = toVC.isBeingPresented ?  endFrame : beginFrame;
                        }
                     completion:^(BOOL finished) {
                         if (toVC.isBeingPresented) {
                             [move removeFromSuperview];
                             toView.frame = endFrame;
                             [container addSubview:toView];
                         }
                         [transitionContext completeTransition: YES];
                     }];
}