Scaffold

sample.packages.flutter.lib.src.material.scaffold.1755.

When the [Scaffold] is actually created in the same build function, the context argument to the build function can't be used to find the [Scaffold] (since it's "above" the widget being returned in the widget tree). In such cases, the following technique with a [Builder] can be used to provide a new scope with a [BuildContext] that is "under" the [Scaffold]:

  
import 'package:flutter/material.dart';

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  static const String _title = 'Flutter Code Sample';

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      title: _title,
      home: MyStatelessWidget(),
    );
  }
}

class MyStatelessWidget extends StatelessWidget {
  const MyStatelessWidget({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Demo')),
      body: Builder(
        // Create an inner BuildContext so that the onPressed methods
        // can refer to the Scaffold with Scaffold.of().
        builder: (BuildContext context) {
          return Center(
            child: ElevatedButton(
              child: const Text('SHOW BOTTOM SHEET'),
              onPressed: () {
                Scaffold.of(context).showBottomSheet(
                  (BuildContext context) {
                    return Container(
                      alignment: Alignment.center,
                      height: 200,
                      color: Colors.amber,
                      child: Center(
                        child: Column(
                          mainAxisSize: MainAxisSize.min,
                          children: [
                            const Text('BottomSheet'),
                            ElevatedButton(
                              child: const Text('Close BottomSheet'),
                              onPressed: () {
                                Navigator.pop(context);
                              },
                            ),
                          ],
                        ),
                      ),
                    );
                  },
                );
              },
            ),
          );
        },
      ),
    );
  }
}
  

SHARE: