1. override
AnimationController createAnimationController()

Called to create the animation controller that will drive the transitions to this route from the previous one, and back to the previous route from this one.

Source

@override
AnimationController createAnimationController() {
  AnimationController controller = super.createAnimationController();
  if (settings.isInitialRoute)
    controller.value = 1.0;
  return controller;
}