Implemented NestedWillPopScope for later handling PopScopes

README.md

@@ -218,6 +218,19 @@ If you are pushing a new `modal` screen, use the following function:
 
 - To push bottom sheet on top of the Navigation Bar, use showModalBottomScreen and set it's property `useRootNavigator` to true. See example project for an illustration.
 
+- To handle PopScopes down in the widget tree just implement 'NestedWillPopScope':
+
+    ```dart
+        import 'package:persistent_bottom_nav_bar/models/nested_will_pop_scope.dart';
+
+        NestedWillPopScope(
+        onWillPop: () async {
+            'your statements to handle PopScope'
+        },
+        child: ThirdNestedScreen(),
+        );
+     ```
+
 ## Custom Navigation Bar Styling
 
 If you want to have your own style for the navigation bar, follow these steps:

example/pubspec.lock

@@ -7,7 +7,7 @@ packages:
       name: async
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.5.0"
+    version: "2.6.1"
   boolean_selector:
     dependency: transitive
     description:
@@ -99,7 +99,7 @@ packages:
       name: source_span
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.8.0"
+    version: "1.8.1"
   stack_trace:
     dependency: transitive
     description:
@@ -134,7 +134,7 @@ packages:
       name: test_api
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.2.19"
+    version: "0.3.0"
   typed_data:
     dependency: transitive
     description:

lib/models/nested_will_pop_scope.dart

@@ -0,0 +1,67 @@
+import 'package:flutter/material.dart';
+
+class NestedWillPopScope extends StatefulWidget {
+  const NestedWillPopScope({
+    Key? key,
+    required this.child,
+    required this.onWillPop,
+  }) : super(key: key);
+
+  final Widget child;
+  final WillPopCallback onWillPop;
+
+  @override
+  _NestedWillPopScopeState createState() => _NestedWillPopScopeState();
+
+  static _NestedWillPopScopeState? of(BuildContext context) {
+    return context.findAncestorStateOfType<_NestedWillPopScopeState>();
+  }
+}
+
+class _NestedWillPopScopeState extends State<NestedWillPopScope> {
+  ModalRoute<dynamic>? _route;
+
+  _NestedWillPopScopeState? _descendant;
+
+  //ignore: avoid_setters_without_getters
+  set descendant(_NestedWillPopScopeState state) {
+    _descendant = state;
+    updateRouteCallback();
+  }
+
+  Future<bool> onWillPop() async {
+    bool? willPop;
+    if (_descendant != null) {
+      willPop = await _descendant!.onWillPop();
+    }
+    if (willPop == null || willPop) {
+      willPop = await widget.onWillPop();
+    }
+    return willPop;
+  }
+
+  void updateRouteCallback() {
+    _route?.removeScopedWillPopCallback(onWillPop);
+    _route = ModalRoute.of(context);
+    _route?.addScopedWillPopCallback(onWillPop);
+  }
+
+  @override
+  void didChangeDependencies() {
+    super.didChangeDependencies();
+    final parentGuard = NestedWillPopScope.of(context);
+    if (parentGuard != null) {
+      parentGuard.descendant = this;
+    }
+    updateRouteCallback();
+  }
+
+  @override
+  void dispose() {
+    _route?.removeScopedWillPopCallback(onWillPop);
+    super.dispose();
+  }
+
+  @override
+  Widget build(BuildContext context) => widget.child;
+}

lib/persistent-tab-view.dart

@@ -6,6 +6,8 @@ import 'dart:ui';
 import 'package:flutter/cupertino.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/cupertino.dart' show CupertinoApp;
+import 'models/nested_will_pop_scope.dart';
+
 
 //Main TabView Widget
 part 'persistent-tab-view.widget.dart';

lib/persistent-tab-view.widget.dart

@@ -667,11 +667,11 @@ class _PersistentTabViewState extends State<PersistentTabView> {
     }
 
     if (widget.handleAndroidBackButtonPress || widget.onWillPop != null) {
-      return WillPopScope(
+      return NestedWillPopScope(
         onWillPop: !widget.handleAndroidBackButtonPress &&
                 widget.onWillPop != null
             ? widget.onWillPop!(_contextList[_controller!.index])
-                as Future<bool> Function()?
+                as Future<bool> Function()
             : widget.handleAndroidBackButtonPress && widget.onWillPop != null
                 ? () async {
                     if (_controller!.index == 0 &&

pubspec.lock

@@ -7,7 +7,7 @@ packages:
       name: async
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "2.5.0"
+    version: "2.6.1"
   boolean_selector:
     dependency: transitive
     description:
@@ -92,7 +92,7 @@ packages:
       name: source_span
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "1.8.0"
+    version: "1.8.1"
   stack_trace:
     dependency: transitive
     description:
@@ -127,7 +127,7 @@ packages:
       name: test_api
       url: "https://pub.dartlang.org"
     source: hosted
-    version: "0.2.19"
+    version: "0.3.0"
   typed_data:
     dependency: transitive
     description: