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<topic_start>
What is the equivalent of Nuget? How do I add dependencies?
In the .NET ecosystem, native Xamarin projects and Xamarin.Forms projects
had access to Nuget and the built-in package management system.
Flutter apps contain a native Android app, native iOS app and Flutter app.In Android, you add dependencies by adding to your Gradle build script.
In iOS, you add dependencies by adding to your Podfile.Flutter uses Dart’s own build system, and the Pub package manager.
The tools delegate the building of the native Android and iOS wrapper apps
to the respective build systems.In general, use pubspec.yaml to declare
external dependencies to use in Flutter.
A good place to find Flutter packages is on pub.dev.<topic_end>
<topic_start>
Application lifecycle
<topic_end>
<topic_start>
How do I listen to application lifecycle events?
In Xamarin.Forms, you have an Application
that contains OnStart, OnResume and OnSleep.
In Flutter, you can instead listen to similar lifecycle events
by hooking into the WidgetsBinding observer and listening to
the didChangeAppLifecycleState() change event.The observable lifecycle events are:For more details on the meaning of these states,
see the AppLifecycleStatus documentation.<topic_end>
<topic_start>
Layouts
<topic_end>
<topic_start>
What is the equivalent of a StackLayout?
In Xamarin.Forms you can create a StackLayout
with an Orientation of horizontal or vertical.
Flutter has a similar approach,
however you would use the Row or Column widgets.If you notice the two code samples are identical
except the Row and Column widget.
The children are the same and this feature
can be exploited to develop rich layouts
that can change overtime with the same children.
<code_start>@override
Widget build(BuildContext context) {
return const Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text('Row One'),
Text('Row Two'),
Text('Row Three'),
Text('Row Four'),
],
);
}<code_end>
<code_start>@override
Widget build(BuildContext context) {
return const Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text('Column One'),
Text('Column Two'),
Text('Column Three'),
Text('Column Four'),
],
);<code_end>
<topic_end>
<topic_start>
What is the equivalent of a Grid?
The closest equivalent of a Grid would be a GridView.
This is much more powerful than what you are used to in Xamarin.Forms.
A GridView provides automatic scrolling when the
content exceeds its viewable space.
<code_start>@override
Widget build(BuildContext context) {
return GridView.count(
// Create a grid with 2 columns. If you change the scrollDirection to
// horizontal, this would produce 2 rows.
crossAxisCount: 2,
// Generate 100 widgets that display their index in the list.
children: List<Widget>.generate(
100,
(index) {
return Center(
child: Text(
'Item $index',
style: Theme.of(context).textTheme.headlineMedium,
),
);
},
),
);
}<code_end>
You might have used a Grid in Xamarin.Forms
to implement widgets that overlay other widgets.
In Flutter, you accomplish this with the Stack widget.This sample creates two icons that overlap each other.
<code_start>@override
Widget build(BuildContext context) {
return const Stack(
children: <Widget>[
Icon(
Icons.add_box,
size: 24,
color: Colors.black,
),
Positioned(
left: 10,
child: Icon(
Icons.add_circle,