text
stringlengths 1
372
|
---|
Icon(CupertinoIcons.arrow_down_square),
|
Icon(CupertinoIcons.arrow_up_square),
|
Text('Row 2'),
|
Icon(CupertinoIcons.arrow_down_square),
|
Icon(CupertinoIcons.arrow_up_square),
|
];
|
class HomePage extends StatelessWidget {
|
const HomePage({super.key});
|
@override
|
widget build(BuildContext context) {
|
return scaffold(
|
body: GridView.builder(
|
gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount(
|
crossAxisCount: 3,
|
mainAxisExtent: 40,
|
),
|
itemCount: widgets.length,
|
itemBuilder: (context, index) => widgets[index],
|
),
|
);
|
}
|
}
|
<code_end>
|
the SliverGridDelegateWithFixedCrossAxisCount delegate determines
|
various parameters that the grid uses to lay out its components.
|
this includes crossAxisCount that dictates the number of items
|
displayed on each row.
|
how SwiftUI’s grid and flutter’s GridView differ in that grid
|
requires GridRow. GridView uses the delegate to decide how the
|
grid should lay out its components.
|
<topic_end>
|
<topic_start>
|
creating a scroll view
|
in SwiftUI, you use ScrollView to create custom scrolling
|
components.
|
the following example displays a series of PersonView instances
|
in a scrollable fashion.
|
to create a scrolling view, flutter uses SingleChildScrollView.
|
in the following example, the function mockPerson mocks instances
|
of the person class to create the custom PersonView widget.
|
<code_start>
|
SingleChildScrollView(
|
child: column(
|
children: mockPersons
|
.map(
|
(person) => PersonView(
|
person: person,
|
),
|
)
|
.tolist(),
|
),
|
),
|
<code_end>
|
<topic_end>
|
<topic_start>
|
responsive and adaptive design
|
in SwiftUI, you use GeometryReader to create relative view sizes.
|
for example, you could:
|
you can also see if the size class has .regular or .compact
|
using horizontalSizeClass.
|
to create relative views in flutter, you can use one of two options:
|
to learn more, check out creating responsive and adaptive apps.
|
<topic_end>
|
<topic_start>
|
managing state
|
in SwiftUI, you use the @state property wrapper to represent the
|
internal state of a SwiftUI view.
|
SwiftUI also includes several options for more complex state
|
management such as the ObservableObject protocol.
|
flutter manages local state using a StatefulWidget.
|
implement a stateful widget with the following two classes:
|
the state object stores the widget’s state.
|
to change a widget’s state, call setState() from the state subclass
|
to tell the framework to redraw the widget.
|
the following example shows a part of a counter app:
|
<code_start>
|
class MyHomePage extends StatefulWidget {
|
const MyHomePage({super.key});
|
@override
|
State<MyHomePage> createState() => _MyHomePageState();
|
}
|
class _MyHomePageState extends State<MyHomePage> {
|
int _counter = 0;
|
@override
|
widget build(BuildContext context) {
|
return scaffold(
|
body: center(
|
child: column(
|
mainAxisAlignment: MainAxisAlignment.center,
|
children: [
|
text('$_counter'),
|
TextButton(
|
onPressed: () => setState(() {
|
_counter++;
|
}),
|
child: const text('+'),
|
),
|
],
|
),
|
),
|
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