Flutter CustomMaterialPageRoute not calling onWillPop after swipe right

Question

I am attempting to have a list screen return am array of selected items to a prior screen. No problem in Android, but no luck in iOS. The right swipe does not call the onWillPop function that returns an array of selected items from the list.

1. I have created a CustomMaterialPageRoute:

    class CustomMaterialPageRoute extends MaterialPageRoute { @protected bool get hasScopedWillPopCallback { return false; } CustomMaterialPageRoute({ required WidgetBuilder builder, required RouteSettings settings, bool maintainState = true, bool fullscreenDialog = false, }) : super( builder: builder, settings: settings, maintainState: maintainState, fullscreenDialog: fullscreenDialog, ); }

2. I call the list screen via:

    void _getTurnpointsForTask() async { final result = await Navigator.pushNamed(context,TurnpointsForTask.routeName, arguments: TurnpointsSearchInAppBarScreen.TASK_TURNPOINT_OPTION,); if (result is List<Turnpoint>) { // result comes back null. BlocProvider.of<TaskBloc>(context).add(TurnpointsAddedToTaskEvent(result)); } }

3. The route code is:

    if (settings.name == TurnpointsForTask.routeName) { final viewOption = settings.arguments as String; return CustomMaterialPageRoute( builder: (context) { return TurnpointsForTask(viewOption: viewOption); }, settings: settings, );

   }

4. The list screen build starts with:

    @override Widget build(BuildContext context) { return ConditionalWillPopScope( onWillPop: _onWillPop, shouldAddCallback: widget._hasChanges, //<_hasChanges is true child: Scaffold( key: _scaffoldKey, ...

5. The _onWillPop code which is called with Android back button, but not with iOS right swipe:

    Future<bool> _onWillPop() async { if (widget.viewOption == TurnpointsSearchInAppBarScreen.TASK_TURNPOINT_OPTION) { ScaffoldMessenger.of(context).removeCurrentSnackBar(); Navigator.of(context).pop(widget.turnpointsForTask); <<< return array of items } else { Navigator.of(context).pop(); } return true; }

What am I missing?

Answer 1

Not sure this is the best solution, but it works.

@override
Widget build(BuildContext context) {
if (Platform.isAndroid) {
  return ConditionalWillPopScope(
    onWillPop: _onWillPop,
    shouldAddCallback: true,
    child: _buildScaffold(context),
  );
} else {
  //iOS
  return GestureDetector(
    behavior: HitTestBehavior.deferToChild,  // if you have lower level drag/drop widgets
    onHorizontalDragUpdate: (details) {
      if (details.delta.direction >= 0) {
        _onWillPop();
      }
    },
    child: _buildScaffold(context),
  );
}

}