Flutter, how to use confirmDismiss in Dismissible?

Question

What I have:

Dismissible(
    key: Key(state.threads[index].toString()),
    onDismissed: (direction) {
        setState(() {
            state.threads.removeAt         


        

Answer 1

I used the below code in a project where I could Archive or Delete notifications. @Yurij Kots answer along with the flutter interactive example found here Example from Flutter's Docs: CookBook

See image. If you pull right or left it shows you an underlying ICON that is below the item... telling you "what might happen"!

TO WATCH THE CODE WORK: Just past the entire code below at the link's interactive example coding space.

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatefulWidget {
  MyApp({Key key}) : super(key: key);

  @override
  MyAppState createState() {
    return MyAppState();
  }
}

class MyAppState extends State {
  final items = List.generate(20, (i) => "Item ${i + 1} A B C D E... X Y Z");

  String whatHappened;

  @override
  Widget build(BuildContext context) {
    final title = 'Notification Items List';

return MaterialApp(
  title: title,
  theme: ThemeData(
    primarySwatch: Colors.blue,
  ),
  home: Scaffold(
    appBar: AppBar(
      title: Text(title),
    ),
    body: ListView.builder(
      itemCount: items.length,
      itemBuilder: (context, index) {
        final item = items[index];

        return Dismissible(            
          key: Key(item),              
          onDismissed: (direction) {               
            setState(() {
              items.removeAt(index);
            });

            Scaffold.of(context)
                .showSnackBar(SnackBar(content: Text("$item was $whatHappened")));
          },






confirmDismiss: (DismissDirection dismissDirection) async {
  switch(dismissDirection) {
    case DismissDirection.endToStart:
      whatHappened = 'ARCHIVED';
      return await _showConfirmationDialog(context, 'Archive') == true;
    case DismissDirection.startToEnd:
      whatHappened = 'DELETED';
      return await _showConfirmationDialog(context, 'Delete') == true;
    case DismissDirection.horizontal:
    case DismissDirection.vertical:
    case DismissDirection.up:
    case DismissDirection.down:
      assert(false);
  }
  return false;
},



          background: Container(
            padding: EdgeInsets.symmetric(horizontal: 12.0),
            color: Colors.red,
            alignment: Alignment.centerLeft,
            child: Icon(Icons.cancel),
          ),
          secondaryBackground: Container(
            padding: EdgeInsets.symmetric(horizontal: 12.0),
            color: Colors.green,
            alignment: Alignment.centerRight,
            child: Icon(Icons.check),
          ),



          child: ListTile(title: Text('$item')),
        );
      },
    ),
  ),
);
  }
}

Future _showConfirmationDialog(BuildContext context, String action) {
  return showDialog(
    context: context,
    barrierDismissible: true,
    builder: (BuildContext context) {
      return AlertDialog(
        title: Text('Do you want to $action this item?'),
        actions: [
          FlatButton(
            child: const Text('Yes'),
            onPressed: () {
              Navigator.pop(context, true); // showDialog() returns true
            },
          ),
          FlatButton(
            child: const Text('No'),
            onPressed: () {
              Navigator.pop(context, false); // showDialog() returns false
            },
          ),
        ],
      );
    },
  );
}