The slide deck of a workshop event at Dec. 11, 2020.

1. Flutter for Beginners
Lesson 1
Build beautiful native apps in record time.

2. Agenda
⚫ Flutter
⚫
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⚫
⚫ APP
⚫ API

3. Flutter
Brief Introduction
print(‘Hello, Flutter’);

4. Flutter
Android IOS
Web Desktop
Flutter Google

6. ”
Flutter 結合了
原生應用程式的效能與品質與
高速開發特性以及跨平台普及性。
“
Flutter

8. Framework
(Dart)
Engine
(C++) Skia Dart Text
Material Cupertino
Widgets
Rendering
Animation Painting Gestures
Foundation
Flutter app
(client)
State
MethodChannel
FlutterMethodChannel
MethodChannel
iOS host
Android host
AppDelegate
Activity
FlutterViewController
FlutterView
iOS
Platform
APIs
3rd-Party
APIs for
iOS
Android
Platform
APIs
3rd-Party
APIs for
Android

9. Your First Flutter App
And now, you’re going to see the future.

10. New Flutter Project
Step 1 Step 2 Step 3
• Flutter •
• Flutter SDK
•
•
•
Tip: If you don’t see “New Flutter Project” as
an option in your IDE, make sure you have
the plugins installed for Flutter and Dart.

11. import 'package:flutter/material.dart';
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
// This is the theme of your application.
//
// Try running your application with "flutter run". You'll see the
// application has a blue toolbar. Then, without quitting the app, try
// changing the primarySwatch below to Colors.green and then invoke
// "hot reload" (press "r" in the console where you ran "flutter run",
// or simply save your changes to "hot reload" in a Flutter IDE).
// Notice that the counter didn't reset back to zero; the application
// is not restarted.
primarySwatch: Colors.blue,
// This makes the visual density adapt to the platform that you run
// the app on. For desktop platforms, the controls will be smaller and
// closer together (more dense) than on mobile platforms.
visualDensity: VisualDensity.adaptivePlatformDensity,
),
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
// This widget is the home page of your application. It is stateful, meaning
// that it has a State object (defined below) that contains fields that affect
// how it looks.
// This class is the configuration for the state. It holds the values (in this

12. Project Structure
Made with ❤ by Flutter community.

13. Project Window
/lib/main.dart
/pubspec.ymal
lib dart
main.dart
pubspec.ymal

14. main.dart
void main() => runApp(MyApp());
runApp(<widget>);
MyApp 繼承 StatelessWidget
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
home: MyHomePage(title: 'Flutter Demo Home Page'),
);
}
}

15. pubspec.yaml
name: flutter_app
description: A new Flutter application.
publish_to: 'none' # Remove this line if you wish to publish to pub.dev
version: 1.0.0+1
environment:
sdk: ">=2.7.0 <3.0.0"
dependencies:
flutter:
sdk: flutter
cupertino_icons: ^1.0.0

16. Everything is a widget.
Layout and Widgets

17. The Widget Tree

18. Material Design

19. MaterialApp
MaterialApp(
title: 'Page Title', // 頁面標題
color: Colors.orange, // 顏色
home: HomePage(), // 主頁面（傳入Widget）
debugShowCheckedModeBanner: false, // 移除 debugModeBanner
theme: ThemeData( // 主題
primaryColor: Colors.blue,
brightness: Brightness.dark,
),
routes: { // 路由
'/home': (context) => HomePage(),
'/about': (context) => AboutPage(),
},
)

20. Scaffold
Scaffold(
appBar: AppBar(), // 標題列
body: Container(), // 主要內容
bottomNavigationBar: BottomAppBar( // 底功能區
shape: const CircularNotchedRectangle(),
child: Container(
height: 50.0,
),
),
floatingActionButton: FloatingActionButton( // 懸浮動作按鈕
onPressed: () {},
child: Icon(Icons.add),
),
floatingActionButtonLocation:
FloatingActionButtonLocation.centerDocked,
)

21. AppBar
appBar: AppBar(
title: Text('Title'),
leading: IconButton(
onPressed: () {},
icon: Icon(Icons.backspace),
),
actions: [
IconButton(
onPressed: () {},
icon: Icon(Icons.add),
),
],
)
* Inside a Scaffold Widget

22. FloatingActionButton
Scaffold(
floatingActionButton: FloatingActionButton(
onPressed: () {
// 按下按鈕後事件
},
backgroundColor: Colors.lightBlue, // 按鈕顏色
child: Container(), // 子組件
),
)
FloatingActionButton.extended(
onPressed: () {
// 按下按鈕後事件
},
backgroundColor: Colors.lightBlue, // 按鈕顏色
icon: Icon(Icons.shopping_bag_outlined), // 圖示
label: Text('BUY’), // 標籤文字
)
* Inside a Scaffold Widget

23. Container /* Container html div
*/
Container(
color: Colors.lightBlue,
width: 100.0,
height: 100.0,
alignment: Alignment.topCenter,
margin: EdgeInsets.all(16.0),
padding: EdgeInsets.zero,
child: Container(),
)

24. Text
Text(
'Text content',
style: TextStyle(),
)

25. Row
Row(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.center,
children: [
Container(),
],
)

26. Column
Column(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.center,
children: [],
)

27. MainAxisAlignment vs. CrossAxisAlignment
MainAxisAlignment.start
MainAxisAlignment.end
MainAxisAlignment.center
MainAxisAlignment.spaceBetween
MainAxisAlignment.spaceAround
MainAxisAlignment.spaceEvenly
Basic Flutter layout concepts
CrossAxisAlignment.start
CrossAxisAlignment.end
CrossAxisAlignment.center
CrossAxisAlignment.stretch

28. Center
Center(
child: Container(),
)

29. Padding *
Padding(
padding: const EdgeInsets.all(8.0),
child: Container(),
)

30. Expanded Row(
children: <Widget>[
Expanded(
flex: 2,
child: Container(
color: Colors.amber,
height: 100,
),
),
Container(
color: Colors.blue,
height: 100,
width: 50,
),
Expanded(
flex: 1,
child: Container(
color: Colors.amber,
height: 100,
),
),
],
)

31. Image
Image(
image: AssetImage('<file location>'),
)
Image(
image: NetWorkImage('<file URL>'),
)
Image.asset('<file location>')
Image.network(‘<file URL>')
* We need to tell Flutter where the files are located at.
Define it in pubspec.ymal

32. SizedBox *
SizedBox(
height: 100.0,
width: 100.0,
child: Container(),
)

33. Icon *
Icon(Icons.room)

34. Code Like a Pro.
State Management

35. Stateful Widget 透過
createState() 建立
State 的實體，State 類別
使該 Widget 可在生命週
期呼叫 setState()來驅動
build() 方法，進而達到
畫面更新。
StatelessWidget vs. StatefulWidget
class HomePage extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Container();
}
}
class HomePage extends StatefulWidget {
@override
_HomePageState createState() => _HomePageState();
}
class _HomePageState extends State<HomePage> {
@override
Widget build(BuildContext context) {
return Container();
}
}
Stateless Widget 應用於完全不會更
動的畫面，其內部所有變數皆是
final 狀態。

36. More Detail on setState() Method
setState
setState(){};
BMI _height _weight
0 setState
For advanced state management, please refer to:
https://ithelp.ithome.com.tw/articles/10217200
setState(){
_height = 使用者輸入資料;
_weight = 使用者輸入資料;
}
Text(‘Your BMI is ${_weight/_height*_height}’)

37. How to use stateful widget wisely?
1. StatelessWidget
2. StatefulWidget Rebuild
3. setState((){}) State.build() Root
Node Widgets Rebuild
4. Rebuild Widget

38. (12/11/2020)
In-class Practice?

39. ?
Tips:
Scaffold
AppBar
FloatingActionButton & setState Method
Center
Row
Expanded
Image
Dice Image
Download
Source Code

40. The package has been delivered.
Import Packages

41. 1. pub.dev
2. pubspec.ymal
3. pub get
4.
5.

42. pub.dev

43. 14
dependencies:
<Package Name>: ^<Version>
Pub get
Pub get
dev_dependencies

44. import 'package:flutter/material.dart';
import 'package:english_words/english_words.dart';
class HomePage extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: Text(nouns.last),
),
);
}
}
See flutter official documentation here:
https://flutter.dev/docs/development/packages-
and-plugins/using-packages

45. OK, Google. Navigate to home. (or HomePage?)
Navigator & Routing

46. The Difference between Navigator & Router
Navigator Stack push pop
// Within the ‘FirstRoute’ widget
onPressed: () {
Navigator.push( context,
MaterialPageRoute(builder: (context) => SecondRoute()),
);
}
// Within the SecondRoute widget
onPressed: () {
Navigator.pop(context);
}

47. // Navigate to the second screen using a named route.
// Usually place in onPressed(){};
Navigator.pushNamed(context, '/second');
// Navigate back to the first screen by popping the current route
// off the stack.
Navigator.pop(context);
Router
The Difference between Navigator & Router (cont.)

48. Do we need to explain our workflow through flowcharts?
Workflow

50. NUK Plus GitHub Repo

51. HTTP/1.1 200 OK
API
Connect to an API Server

52. API
Keyword:
● http (flutter package)
● JSON (data transfer format)
● Serialization (data process)
● Future (dart data type)
● async (dart keyword)
● FutureBuilder (flutter widget)
Fetch data from the internet:
https://flutter.dev/docs/cookbook/networki
ng/fetch-data

53. For more info about Flutter, head on over to flutter.dev
Resources

54. Resources
Flutter Official Documentation
● https://flutter.dev/docs
Flutter YouTube Channel
● Widget of the Week
● Flutter in Focus
Online Tutorials
● Udacity
● The App Brewery
The Speaker
Yes, it’s me. Feel free to ask me if you
have any problem on your way to learn
Flutter.
DSC Core Team
We’re here to help you. Contact us by
email, Facebook, or Discord.

55. Stay tuned!
Facebook YouTube DSC Website

56. Developer Student Club
National University of Kaohsiung
感謝聆聽！