Flutter NestedScrollView header bounce with TabBar and TabbarView

Question

1. Header pull to refresh can be pulled up when I want to drag it up.
2. Tabbar sticky.
3. ListView can swipe to another page.

Answer 1

100% Custom Widget. It supports to change the header value and also support swipe opeartions.

It is not actually a TabBar Widget but it Works exactly like that

     import 'package:flutter/material.dart';

import 'dart:math';


class NestedScrolls extends StatefulWidget {
static const   listHeader = ['Pakistan', 'China','Iran','Turkey'];
  @override
  _NestedScrollsState createState() => _NestedScrollsState();
}

class _NestedScrollsState extends State<NestedScrolls> {
 

var position=0;
  var topHeader;
 Widget? applyWidget() {

   switch(position){
     case 0:
       setState(() {
         topHeader = NestedScrolls.listHeader[0];
       });
       // return widget if user click over pakistan in tab bar
       return grid();
     case 1:
       setState(() {
         topHeader = NestedScrolls.listHeader[1];
       });
       return   list();
     case 2:
       setState(() {
         topHeader = NestedScrolls.listHeader[2];
       });
       return Container(color: Colors.blue,
         child: Center(child: Text(topHeader),),);
     case 3:
       setState(() {
         topHeader = NestedScrolls.listHeader[3];
       });
       return Container(color: Colors.orange,
         child: Center(child: Text(topHeader),),);


   }



  }
@override
  void initState() {
    // TODO: implement initState
    super.initState();
    //initial header name when activity start first time
     topHeader = NestedScrolls.listHeader[0];
  }
  @override
  Widget build(BuildContext context) {
    topHeader = topHeader;
    return Scaffold(
      // Persistent AppBar that never scrolls
      appBar: AppBar(
        title: Text('AppBar'),
        elevation: 0.0,
      ),
      body:
           Column(
            children: <Widget>[
              ///header
              Container(
                alignment: Alignment.center,
                color: Colors.blueGrey,
                height: 90,
                child: Text(NestedScrolls.listHeader[position]),
              ),
              /// tabBar
              Container(
                height: 60,
                width: MediaQuery.of(context).size.width,
                child: ListView.builder(
                    scrollDirection: Axis.horizontal,
                    itemCount: NestedScrolls.listHeader.length,
                    itemBuilder: (con, index) {
                      return GestureDetector(
                        onTap: () => setState(() {
                          position=index;
                          topHeader = NestedScrolls.listHeader[index];

                        }),
                        child: Padding(
                          padding: const EdgeInsets.symmetric(
                              vertical: 2.0, horizontal: 10),
                          child: Container(alignment: Alignment.center,
                              width: 100,
                              color: topHeader==NestedScrolls.listHeader[index]?Colors.black26:Colors.transparent,
                              child: Text(NestedScrolls.listHeader[index])),
                        ),
                      );
                    }),
              ),

            ///Widget
            Expanded(
                  child: GestureDetector(

                      // onHorizontalDragStart: (left){
                      //    print('left : ${left.localPosition.direction}');
                      // // left.globalPosition.dx
                      //
                      // },
                      onHorizontalDragEnd: (start){
                        print('start : ${start.velocity.pixelsPerSecond.dx}');
                        if((start.velocity.pixelsPerSecond.dx)<-700){
                          if(position<NestedScrolls.listHeader.length-1 && position>=0)
                            setState(() {
                              position=position+1;
                            });


                        }else{}

                      if((start.velocity.pixelsPerSecond.dx)>900){
                        if(position<=NestedScrolls.listHeader.length-1 && position>0)
                          setState(() {
                            position=position-1;
                          });

                        }
                        print(position);
                      },
                      child: applyWidget()),
                ),

            ],
          ),
    );
  }

  list() {
    return SingleChildScrollView(scrollDirection: Axis.vertical,
      child: Container(



              child: Column(children: [
                for(var color in Colors.primaries)
                Container(color: color, height: 100.0)

              ],),






      ),
    );
  }

  grid() {
    return  GridView.count(
        padding: EdgeInsets.zero,
        crossAxisCount: 3,
        children: Colors.primaries.map((color) {
          return Container(color: color, height: 100.0);
        }).toList(),
      );
  }
}