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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, |
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