didChangePrevious method

@override void didChangePrevious(Route? previousRoute)

This route's previous route has changed to the given new route.

This is called on a route whenever the previous route changes for any reason, so long as it is in the history, except for immediately after the route itself has been pushed (in which case didPush or didReplace will be called instead).

The previousRoute argument will be null if there's no previous route (i.e. if isFirst is true).

Implementation

@override
void didChangePrevious(Route<dynamic>? previousRoute) {
  final previousTitleString = previousRoute is CupertinoRouteTransitionMixin
      ? previousRoute.title
      : null;
  if (_previousTitle == null) {
    _previousTitle = ValueNotifier<String?>(previousTitleString);
  } else {
    _previousTitle!.value = previousTitleString;
  }
  super.didChangePrevious(previousRoute);
}