Refresh Indicator between SliverAppBar and SliverList (Like Instagram refresh) in Flutter

RefreshIndicatorExample.dart

CustomScrollView(
      physics:
          const BouncingScrollPhysics(parent: AlwaysScrollableScrollPhysics()),
      slivers: <Widget>[
        SliverAppBar(
          title: Text(
            "Example",
            style: heading1,
          ),
          floating: true,
          elevation: 3,
          forceElevated: true,
          backgroundColor: backgroundWhite,
        ),
        CupertinoSliverRefreshControl(
        
          onRefresh: () async {
            await Future.delayed(Duration(seconds: 2));
          },
        ),
        SliverList(
          delegate: SliverChildBuilderDelegate(
            (BuildContext context, int index) {
              return Container(
                  color: Colors
                      .primaries[Random().nextInt(Colors.primaries.length)],
                  height: 150.0);
            },
          ),
        )
      ],
    );