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user interface it represents.
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It’s common to begin your app with a WidgetApp class,
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like CupertinoApp.
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<code_start>class MyApp extends StatelessWidget {
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const MyApp({super.key});
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@override
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Widget build(BuildContext context) {
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// Returns a CupertinoApp that, by default,
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// has the look and feel of an iOS app.
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return const CupertinoApp(
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home: HomePage(),
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);
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}
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}<code_end>
|
The widget used in HomePage might begin with the Scaffold class.
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Scaffold implements a basic layout structure for an app.
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<code_start>class HomePage extends StatelessWidget {
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const HomePage({super.key});
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@override
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Widget build(BuildContext context) {
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return const Scaffold(
|
body: Center(
|
child: Text(
|
'Hello, World!',
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),
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),
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);
|
}
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}<code_end>
|
Note how Flutter uses the Center widget.
|
SwiftUI renders a view’s contents in its center by default.
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That’s not always the case with Flutter.
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Scaffold doesn’t render its body widget at the center of the screen.
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To center the text, wrap it in a Center widget.
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To learn about different widgets and their default behaviors, check out
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the Widget catalog.<topic_end>
|
<topic_start>
|
Adding Buttons
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In SwiftUI, you use the Button struct to create a button.To achieve the same result in Flutter,
|
use the CupertinoButton class:
|
<code_start> CupertinoButton(
|
onPressed: () {
|
// This closure is called when your button is tapped.
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},
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child: const Text('Do something'),
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)<code_end>
|
Flutter gives you access to a variety of buttons with predefined styles.
|
The CupertinoButton class comes from the Cupertino library.
|
Widgets in the Cupertino library use Apple’s design system.<topic_end>
|
<topic_start>
|
Aligning components horizontally
|
In SwiftUI, stack views play a big part in designing your layouts.
|
Two separate structures allow you to create stacks:HStack for horizontal stack viewsVStack for vertical stack viewsThe following SwiftUI view adds a globe image and
|
text to a horizontal stack view:Flutter uses Row rather than HStack:
|
<code_start> Row(
|
mainAxisAlignment: MainAxisAlignment.center,
|
children: [
|
Icon(CupertinoIcons.globe),
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Text('Hello, world!'),
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],
|
),<code_end>
|
The Row widget requires a List<Widget> in the children parameter.
|
The mainAxisAlignment property tells Flutter how to position children
|
with extra space. MainAxisAlignment.center positions children in the
|
center of the main axis. For Row, the main axis is the horizontal
|
axis.<topic_end>
|
<topic_start>
|
Aligning components vertically
|
The following examples build on those in the previous section.In SwiftUI, you use VStack to arrange the components into a
|
vertical pillar.Flutter uses the same Dart code from the previous example,
|
except it swaps Column for Row:
|
<code_start> Column(
|
mainAxisAlignment: MainAxisAlignment.center,
|
children: [
|
Icon(CupertinoIcons.globe),
|
Text('Hello, world!'),
|
],
|
),<code_end>
|
<topic_end>
|
<topic_start>
|
Displaying a list view
|
In SwiftUI, you use the List base component to display sequences
|
of items.
|
To display a sequence of model objects, make sure that the user can
|
identify your model objects.
|
To make an object identifiable, use the Identifiable protocol.This resembles how Flutter prefers to build its list widgets.
|
Flutter doesn’t need the list items to be identifiable.
|
You set the number of items to display then build a widget for each item.
|
<code_start>class Person {
|
String name;
|
Person(this.name);
|
}
|
var items = [
|
Person('Person 1'),
|
Person('Person 2'),
|
Person('Person 3'),
|
];
|
class HomePage extends StatelessWidget {
|
const HomePage({super.key});
|
@override
|
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