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Flutter_Documentation

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Use a Navigator to move between different Routes
that represent different screens or pages,
or maybe different states or renderings of the same data.<topic_end>
<topic_start>
Listening to lifecycle events
In UIKit, you can override methods to the ViewController
to capture lifecycle methods for the view itself,
or register lifecycle callbacks in the AppDelegate.
In Flutter, you have neither concept, but you can instead
listen to lifecycle events by hooking into
the WidgetsBinding observer and listening to
the didChangeAppLifecycleState() change event.The observable lifecycle events are:For more details on the meaning of these states, see
AppLifecycleState documentation.<topic_end>
<topic_start>
Layouts
This section discusses different layouts in Flutter
and how they compare with UIKit.<topic_end>
<topic_start>
Displaying a list view
In UIKit, you might show a list in
either a UITableView or a UICollectionView.
In Flutter, you have a similar implementation using a ListView.
In UIKit, these views have delegate methods
for deciding the number of rows,
the cell for each index path, and the size of the cells.Due to Flutter’s immutable widget pattern,
you pass a list of widgets to your ListView,
and Flutter takes care of making sure that
scrolling is fast and smooth.
<code_start>import 'package:flutter/material.dart';
void main() {
runApp(const SampleApp());
}
class SampleApp extends StatelessWidget {
const SampleApp({super.key});
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return const MaterialApp(
title: 'Sample App',
home: SampleAppPage(),
);
}
}
class SampleAppPage extends StatefulWidget {
const SampleAppPage({super.key});
@override
State<SampleAppPage> createState() => _SampleAppPageState();
}
class _SampleAppPageState extends State<SampleAppPage> {
List<Widget> _getListData() {
final List<Widget> widgets = [];
for (int i = 0; i < 100; i++) {
widgets.add(Padding(
padding: const EdgeInsets.all(10),
child: Text('Row $i'),
));
}
return widgets;
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: const Text('Sample App'),
),
body: ListView(children: _getListData()),
);
}
}<code_end>
<topic_end>
<topic_start>
Detecting what was clicked
In UIKit, you implement the delegate method,
tableView:didSelectRowAtIndexPath:.
In Flutter, use the touch handling provided by the passed-in widgets.
<code_start>import 'dart:developer' as developer;
import 'package:flutter/material.dart';
void main() {
runApp(const SampleApp());
}
class SampleApp extends StatelessWidget {
const SampleApp({super.key});
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return const MaterialApp(
title: 'Sample App',
home: SampleAppPage(),
);
}
}
class SampleAppPage extends StatefulWidget {
const SampleAppPage({super.key});
@override
State<SampleAppPage> createState() => _SampleAppPageState();
}
class _SampleAppPageState extends State<SampleAppPage> {
List<Widget> _getListData() {
List<Widget> widgets = [];
for (int i = 0; i < 100; i++) {