Present 2 viewcontrollers but only one transition

Question

I want to push from a View Controller "A", a second ViewController "B" (with navigation bar) which should show a third modal ViewController "C", which shows a countdown and dismisses itself, to finally show "B".

I would like "C" to be presented modally, without "B" being seen, and when it gets dismissed, "B" should already be there.

I've been looking at this posts:

• Present multiple modal view controllers?
• Presenting a view controller with transparency and animation

But since I need "B" to be pushed (not modal) I can't use UIModalPresentationCurrentContext

I have also tried to do this: How to push two view controllers but animate transition only for the second one?

And it's almost what I want, but I'd like "C" to be presented in a modal style, such as cover vertical.

Answer 1

I finally ended up doing a mix with these two:

• How to push two view controllers but animate transition only for the second one?

  NSMutableArray *controllers = [self.navigationController.viewControllers mutableCopy];
  UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Main" bundle:nil];
  
  MyCViewController *vcC = [storyboard instantiateViewControllerWithIdentifier:IDENTIFIER_VC];
  MyBViewController *vcB = [storyboard instantiateViewControllerWithIdentifier:IDENTIFIER_VC];
  
  [controllers addObject:vcC];
  [controllers addObject:vcB];
  
  self.navigationController.delegate = vcB;
  [self.navigationController setViewControllers:controllers animated:YES];
  

• https://www.objc.io/issues/5-ios7/view-controller-transitions/

In vcB:

    -(id<UIViewControllerAnimatedTransitioning>)navigationController:(UINavigationController *)navigationController animationControllerForOperation:(UINavigationControllerOperation)operation fromViewController:(UIViewController *)fromVC toViewController:(UIViewController *)toVC
    {
        if (operation == UINavigationControllerOperationPush || operation == UINavigationControllerOperationPop) {
            MyAnimator *animator = [[MyAnimator alloc] init];
            animator.presenting = (operation == UINavigationControllerOperationPush);
            return animator;
        }
        return nil;
    }

In MyAnimator.m:

-(NSTimeInterval)transitionDuration:(id<UIViewControllerContextTransitioning>)transitionContext
{
    return 0.4;
}

-(void)animateTransition:(id<UIViewControllerContextTransitioning>)transitionContext
{
    UIViewController *fromViewController = [transitionContext viewControllerForKey:UITransitionContextFromViewControllerKey];
    UIViewController *toViewController = [transitionContext viewControllerForKey:UITransitionContextToViewControllerKey];

    [[transitionContext containerView] addSubview:toViewController.view];

    CGRect currentFrame = toViewController.view.frame;
    CGRect toFrameInitial = self.presenting ? CGRectOffset(currentFrame, 0, CGRectGetHeight(currentFrame)) : CGRectOffset(currentFrame, 0, -CGRectGetHeight(currentFrame));
    CGRect fromFrameFinal = self.presenting ? CGRectOffset(currentFrame, 0, -CGRectGetHeight(currentFrame)) : CGRectOffset(currentFrame, 0,   CGRectGetHeight(currentFrame));

    toViewController.view.frame = toFrameInitial;
    [UIView animateWithDuration:[self    transitionDuration:transitionContext] animations:^{
        toViewController.view.frame = currentFrame;
        fromViewController.view.frame = fromFrameFinal;
    } completion:^(BOOL finished) {
        [transitionContext completeTransition:![transitionContext transitionWasCancelled]];
    }];
}