text
stringlengths 1
372
|
|---|
return null;
|
}
|
return 'not a valid email.';
|
},
|
onSaved: (val) {
|
_email = val;
|
},
|
decoration: const InputDecoration(
|
hintText: 'enter your email',
|
labelText: 'email',
|
),
|
),
|
ElevatedButton(
|
onPressed: _submit,
|
child: const Text('Login'),
|
),
|
],
|
),
|
);
|
}
|
<code_end>
|
the following example shows how form.save() and formKey
|
(which is a GlobalKey), are used to save the form on submit.
|
<code_start>
|
void _submit() {
|
final form = formKey.currentState;
|
if (form != null && form.validate()) {
|
form.save();
|
showDialog(
|
context: context,
|
builder: (context) {
|
return AlertDialog(
|
title: const Text('Alert'),
|
content: Text('Email: $_email, password: $_password'));
|
},
|
);
|
}
|
}
|
<code_end>
|
<topic_end>
|
<topic_start>
|
platform-specific code
|
when building a cross-platform app, you want to re-use as much code as
|
possible across platforms. however, scenarios might arise where it
|
makes sense for the code to be different depending on the OS.
|
this requires a separate implementation by declaring a specific platform.
|
in react native, the following implementation would be used:
|
in flutter, use the following implementation:
|
<code_start>
|
final platform = theme.of(context).platform;
|
if (platform == TargetPlatform.iOS) {
|
return 'ios';
|
}
|
if (platform == TargetPlatform.android) {
|
return 'android';
|
}
|
if (platform == TargetPlatform.fuchsia) {
|
return 'fuchsia';
|
}
|
return 'not recognized ';
|
<code_end>
|
<topic_end>
|
<topic_start>
|
debugging
|
<topic_end>
|
<topic_start>
|
what tools can i use to debug my app in flutter?
|
use the DevTools suite for debugging flutter or dart apps.
|
DevTools includes support for profiling, examining the heap,
|
inspecting the widget tree, logging diagnostics, debugging,
|
observing executed lines of code, debugging memory leaks and memory
|
fragmentation. for more information, see the
|
DevTools documentation.
|
if you’re using an IDE,
|
you can debug your application using the IDE’s debugger.
|
<topic_end>
|
<topic_start>
|
how do i perform a hot reload?
|
flutter’s stateful hot reload feature helps you quickly and easily experiment,
|
build UIs, add features, and fix bugs. instead of recompiling your app
|
every time you make a change, you can hot reload your app instantly.
|
the app is updated to reflect your change,
|
and the current state of the app is preserved.
|
in react native,
|
the shortcut is ⌘r for the iOS simulator and tapping r twice on
|
android emulators.
|
in flutter, if you are using IntelliJ IDE or android studio,
|
you can select save all (⌘s/ctrl-s), or you can click the
|
hot reload button on the toolbar. if you
|
are running the app at the command line using flutter run,
|
type r in the terminal window.
|
you can also perform a full restart by typing r in the
|
terminal window.
|
<topic_end>
|
<topic_start>
|
how do i access the in-app developer menu?
|
in react native, the developer menu can be accessed by shaking your device: ⌘d
|
for the iOS simulator or ⌘m for android emulator.
|
in flutter, if you are using an IDE, you can use the IDE tools. if you start
|
your application using flutter run you can also access the menu by typing h
|
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