content: import 'package:flutter/material.dart';
  import 'package:url_launcher/url_launcher.dart';
  
  class Day11SliverAppBar extends StatefulWidget {
    Day11SliverAppBar({Key key}) : super(key: key);
  
    @override
    _Day11SliverAppBarState createState() => _Day11SliverAppBarState();
  }
  
  class _Day11SliverAppBarState extends State<Day11SliverAppBar> {
    @override
    Widget build(BuildContext context) {
      return Scaffold(
        body: SafeArea(
          child: CustomScrollView(
            slivers: <Widget>[
              SliverAppBar(
                // ? what is SliverAppBar
                /**
                   * ! it is the simple appbar which is used specifically in [CustomScrollView]....
                   * ! you can done many function other then the normal appbar....
                   * ! some of the important are given below....
                   */
                flexibleSpace: const FlexibleSpaceBar(
                  centerTitle: true,
                  title: Text('SliverAppBar'),
                ),
                /**
                   * ! [flexibleSpace] is used to give the fexble app bar....
                   * ! this gives you the cool animation in the appbar like....
                   * ! strink and strech....
                   */
                // ? title: Text("Head"),
                /**
                   * ! [title] to perform the simple appbar text....
                   */
                // ? centerTitle: true,
                /**
                   * ! [centerTitle] to center the text in simple app bar....
                   */
                backgroundColor:
                    Colors.green, // ! to provide the bg color for tha app bar....
                brightness: Brightness
                    .light, // ! to provide the [brightness] like dark or light....
                floating: true, // ! to make the appbar floating...
                elevation: 10.0, // ! to give cool shadow effect....
                expandedHeight: 150.0, // ! max expand or strech size....
                actions: <Widget>[
                  IconButton(
                    icon: Icon(Icons.help),
                    onPressed: () async {
                      const url =
                          'https://github.com/sanjaysanju618/100-Days-Of-Flutter-Widgets/' +
                              'blob/master/hundred_days_of_flutter_widget/' +
                              'lib/day011_sliver_appbar.dart';
                      if (await canLaunch(url)) {
                        await launch(url);
                      } else {
                        throw 'Could not launch $url';
                      }
                    },
                  )
                ],
              ),
              SliverList(
                  // ! these are some of the List elements....
                  // ! we are going to learn it tomorrow....
                  delegate: SliverChildListDelegate([
                ListTile(
                  title: Text("Hello 1"),
                ),
                ListTile(
                  title: Text("Hello 2"),
                ),
                ListTile(
                  title: Text("Hello 3"),
                ),
                ListTile(
                  title: Text("Hello 4"),
                ),
              ])),
            ],
          ),
        ),
      );
    }
  }
  