text stringlengths 1 474 |
|---|
} |
bool isEmail(String em) { |
const String emailRegexp = |
r'^(([^<>()[\]\\.,;:\s@\"]+(\.[^<>()[\]\\.,;:\s@\"]+)*)|' |
r'(\".+\"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\])|' |
r'(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$'; |
final RegExp regExp = RegExp(emailRegexp); |
return regExp.hasMatch(em); |
} |
@override |
Widget build(BuildContext context) { |
return Scaffold( |
appBar: AppBar(title: const Text('Sample App')), |
body: Center( |
child: TextField( |
onSubmitted: (text) { |
setState(() { |
if (!isEmail(text)) { |
_errorText = 'Error: This is not an email'; |
} else { |
_errorText = null; |
} |
}); |
}, |
decoration: InputDecoration( |
hintText: 'This is a hint', |
errorText: _getErrorText(), |
), |
), |
), |
); |
} |
}<code_end> |
<topic_end> |
<topic_start> |
Flutter plugins |
<topic_end> |
<topic_start> |
Interacting with hardware, third party services, and the platform |
<topic_end> |
<topic_start> |
How do I interact with the platform, and with platform native code? |
Flutter doesn’t run code directly on the underlying platform; |
rather, the Dart code that makes up a Flutter app is run natively |
on the device, “sidestepping” the SDK provided by the platform. |
That means, for example, when you perform a network request in Dart, |
it runs directly in the Dart context. |
You don’t use the Android or iOS APIs |
you normally take advantage of when writing native apps. |
Your Flutter app is still hosted in a native app’s |
ViewController or Activity as a view, |
but you don’t have direct access to this, or the native framework.This doesn’t mean Flutter apps can’t interact with those native APIs, |
or with any native code you have. Flutter provides platform channels |
that communicate and exchange data with the |
ViewController or Activity that hosts your Flutter view. |
Platform channels are essentially an asynchronous messaging mechanism |
that bridges the Dart code with the host ViewController |
or Activity and the iOS or Android framework it runs on. |
You can use platform channels to execute a method on the native side, |
or to retrieve some data from the device’s sensors, for example.In addition to directly using platform channels, |
you can use a variety of pre-made plugins |
that encapsulate the native and Dart code for a specific goal. |
For example, you can use a plugin to access |
the camera roll and the device camera directly from Flutter, |
without having to write your own integration. |
Plugins are found on pub.dev, |
Dart and Flutter’s open source package repository. |
Some packages might support native integrations on iOS, |
or Android, or both.If you can’t find a plugin on pub.dev that fits your needs, |
you can write your own, and publish it on pub.dev.<topic_end> |
<topic_start> |
How do I access the GPS sensor? |
Use the geolocator community plugin.<topic_end> |
<topic_start> |
How do I access the camera? |
The camera plugin is popular for accessing the camera.<topic_end> |
<topic_start> |
How do I log in with Facebook? |
To log in with Facebook, use the |
flutter_facebook_login community plugin.<topic_end> |
<topic_start> |
How do I use Firebase features? |
Most Firebase functions are covered by first party plugins. |
These plugins are first-party integrations, maintained by the Flutter team:You can also find some third-party Firebase plugins on pub.dev |
that cover areas not directly covered by the first-party plugins.<topic_end> |
<topic_start> |
How do I build my own custom native integrations? |
If there is platform-specific functionality that Flutter |
or its community plugins are missing, |
you can build your own following the |
developing packages and plugins page.Flutter’s plugin architecture, in a nutshell, |
is much like using an Event bus in Android: |
you fire off a message and let the receiver process and emit a result |
back to you. In this case, the receiver is code running on the native side |
on Android or iOS.<topic_end> |
<topic_start> |
Themes (Styles) |
<topic_end> |
<topic_start> |
How do I theme my app? |
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