showModalBottomSheet Widget

bottomsheet.dart

import 'package:flutter/material.dart';

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
      
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,  // to remove debug flag
      home: Scaffold(
          resizeToAvoidBottomPadding: false,
          //backgroundColor:  Colors.white,
        body: SafeArea(
          child: MyHome()
          ),  // SafeArea  
        ), // Scaffold
    ); // MaterialApp
    
   
  }
}

//BottomSheet
class MyHome extends StatefulWidget {
  @override
  _MyHomeState createState() => _MyHomeState();
}

class _MyHomeState extends State<MyHome> {

  BottomSheetApp modal = new BottomSheetApp();
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Container(
        child: Center(child:Text('Hello!',style: TextStyle(fontSize: 72.0,fontWeight: FontWeight.w100 ),))
      ),
     floatingActionButton: FloatingActionButton(
          onPressed: () => modal.mainBottomSheet(context),
          child: Icon(Icons.message),
        ),
    );
  }
}



 import 'package:flutter/material.dart';

 class BottomSheetApp{
   ScrollController _controller = ScrollController();
   mainBottomSheet(BuildContext context){
     showModalBottomSheet(
      //isScrollControlled: true,     //bottomsheet goes full screen, if bottomsheet has a scrollable widget such as a listview as a child.
       shape: RoundedRectangleBorder(
         borderRadius: BorderRadius.circular(30.0),
       ),
       context: context,
       builder: (BuildContext context){
          return 
          Padding(
            padding: EdgeInsets.fromLTRB(10.0, 10.0, 10.0, 10.0),
            child: ListView(
            reverse: true,
            controller: _controller,
            scrollDirection: Axis.vertical,
            children: <Widget>[
              _createTile(context, 'Ok!' , Icons.message , _action1),
              _createTile(context, 'Google' , Icons.message , _action1),
               _createTile(context, 'Say Hi!' , Icons.message , _action1),
              GridView.builder(
                itemCount:9,
                scrollDirection: Axis.vertical,
                shrinkWrap: true,
                itemBuilder:(BuildContext context, int index){
                        return Card(
                          color: Colors.blue[(index % 9) * 100],
                          shape: RoundedRectangleBorder(
                            borderRadius: BorderRadius.circular(20.0),
                          ),
                          child: Container(
                            height: 20.0,
                            width: 20.0,
                            child: Center(child:Text('hello'),),
                          ),
                        );
                    },
                    //padding,
                    gridDelegate:SliverGridDelegateWithFixedCrossAxisCount(crossAxisCount: 3,),
                    
                ),
               
               ],
                            ),
          );
        
                        }
                      );
                    }
                  }






ListTile _createTile(BuildContext context,String name,IconData icon,Function action){
        return ListTile(
          leading: Icon(icon),
          title: Text(name),
          onTap: (){
            Navigator.pop(context);
            action();
          },
        );
 }

 _action1(){
   print('action 1');
 }