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user interface it represents.
It’s common to begin your app with a WidgetApp class,
like CupertinoApp.
<code_start>class MyApp extends StatelessWidget {
const MyApp({super.key});
@override
Widget build(BuildContext context) {
// Returns a CupertinoApp that, by default,
// has the look and feel of an iOS app.
return const CupertinoApp(
home: HomePage(),
);
}
}<code_end>
The widget used in HomePage might begin with the Scaffold class.
Scaffold implements a basic layout structure for an app.
<code_start>class HomePage extends StatelessWidget {
const HomePage({super.key});
@override
Widget build(BuildContext context) {
return const Scaffold(
body: Center(
child: Text(
'Hello, World!',
),
),
);
}
}<code_end>
Note how Flutter uses the Center widget.
SwiftUI renders a view’s contents in its center by default.
That’s not always the case with Flutter.
Scaffold doesn’t render its body widget at the center of the screen.
To center the text, wrap it in a Center widget.
To learn about different widgets and their default behaviors, check out
the Widget catalog.<topic_end>
<topic_start>
Adding Buttons
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.
},
child: const Text('Do something'),
)<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),
Text('Hello, world!'),
],
),<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