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Widget build(BuildContext context) {
return Scaffold(
body: ListView.builder(
itemCount: items.length,
itemBuilder: (context, index) {
return ListTile(
title: Text(items[index].name),
);
},
),
);
}
}<code_end>
Flutter has some caveats for lists:The ListView widget has a builder method.
This works like the ForEach within SwiftUI’s List struct.The itemCount parameter of the ListView sets how many items
the ListView displays.The itemBuilder has an index parameter that will be between zero
and one less than itemCount.The previous example returned a ListTile widget for each item.
The ListTile widget includes properties like height and font-size.
These properties help build a list. However, Flutter allows you to return
almost any widget that represents your data.<topic_end>
<topic_start>
Displaying a grid
When constructing non-conditional grids in SwiftUI,
you use Grid with GridRow.To display grids in Flutter, use the GridView widget.
This widget has various constructors. Each constructor has
a similar goal, but uses different input parameters.
The following example uses the .builder() initializer:
<code_start>const widgets = [
Text('Row 1'),
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(