I made void function and tried to use in Scaffold but it's keeping has Undefined error. I don't get reason about that. give me advice please.
import 'package:auth_practice/secondpage.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:local_auth/local_auth.dart';
void main() => runApp(MaterialApp(
debugShowCheckedModeBanner: false,
home: FingerprintApp(),
));
class FingerprintApp extends StatefulWidget {
const FingerprintApp({Key? key}) : super(key: key);
@override
State<FingerprintApp> createState() => _FingerprintAppState();
}
class _FingerprintAppState extends State<FingerprintApp> {
LocalAuthentication auth = LocalAuthentication();
late bool _canCheckBiometric;
late List<BiometricType> _availableBiometrics; // this list will store all types
//of biometric sensor like face, finger...
String autherized = "Not autherized"; // this String will check if we can
//access our app or not
// Now, create the function that will allow uus to check our biometric sensors
Future<void> _checkBiometric() async{
bool canCheckBiometric;
try{
canCheckBiometric = await auth.canCheckBiometrics;
} on PlatformException catch(e) {
print(e);
}
if(!mounted) return;
setState(() {
_canCheckBiometric = _canCheckBiometric;
});
}
//now that we checked if we are allowed to check our biometric lets get
// the availanle biometrics sensor on our device
Future<void > _getAvailableBiometrics() async{
List<BiometricType> availableBiometric;
try{
availableBiometric = await auth.getAvailableBiometrics();
} on PlatformException catch(e) {
print(e);
}
if(!mounted) return;
setState(() {
_availableBiometrics = availableBiometric;
});
}
Future<void> _authenticate() async {
bool authenticated = false;
try{
authenticated = await auth.authenticateWithBiometrics(
localizedReason: "Scan your finger to authentie",
useErrorDialogs: true,
stickAuth: false
);
}on PlatformException catch(e) {
print(e);
}
if(!mounted) return;
setState(() {
//here we can add what our app will do if the user authenticated first
autherized = authenticated ? "Autherized success" : "Failed to authenticate";
if(authenticated) {
Navigator.push(context, MaterialPageRoute(builder: (context) => SecondPage()));
}
print(autherized);
// note that you must configure your device and add a finger print
});
}
//before we test our app we should first initate the state and call
// our tow first function
@override
void initState() {
//TOdo: implement initstate
_checkBiometric();
_getAvailableBiometrics();
}
@override
Widget build(BuildContext context) {
// TODO: implement build
throw UnimplementedError();
}
}
@override
Widget build(BuildContext context) {
return SafeArea(
child: Scaffold(
backgroundColor: Color(0xfFF3C3E52),
body: Padding(
padding: const EdgeInsets.symmetric(vertical: 12.0, horizontal: 24.0),
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Center(
child: Text("Login,", style: TextStyle(
color: Colors.white,
fontSize: 48.0,
fontWeight: FontWeight.bold
),),
),
Container(
margin: EdgeInsets.symmetric(vertical: 50.0),
child: Column(
children: <Widget>[
Image.asset(
'assets/fingerprint.webp',
width: 120.0,
),
Text("FingerPrint auth", style: TextStyle(
color: Colors.white,
fontSize: 22.0,
fontWeight: FontWeight.bold,
),),
Container(
width: 150.0,
child: Text("Authenticate using your fingerprint instead of your password",
textAlign: TextAlign.center,
style: TextStyle(
color: Colors.white,
height: 1.5
),
),
),
Container(
width: double.infinity,
child: ElevatedButton(
onPressed: _authenticate,
elevation: 0.0,
color: Color(0xFfF04A5ED),
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(30.0),
),
child: Padding(
padding: EdgeInsets.symmetric(vertical: 14.0, horizontal: 24.0),
child: Text("Autentic", style: TextStyle(
color: Colors.white,
),),
),
),
)
],
),
)
],
),
)
)
);
}
}
In Related Question,
- Future _authenticate()
- The ElevatedButton in Widget build(BuildContext context)
Arn't they in same level? I don't get why Button's property doesn't read the function 'authenticate',,
CodePudding user response：
If you are using separate file, 1st remove _ from _authenticate to make it public like authenticate() and import the file on working file and use as
onPressed: authenticate,
CodePudding user response：
Just replace your code with this modified version. The problem in your code is you have two build methods and the one in which you want to pass_authenticate method as onPressed is outside the scope.
import 'package:auth_practice/secondpage.dart';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:local_auth/local_auth.dart';
void main() => runApp(MaterialApp(
debugShowCheckedModeBanner: false,
home: FingerprintApp(),
));
class FingerprintApp extends StatefulWidget {
const FingerprintApp({Key? key}) : super(key: key);
@override
State<FingerprintApp> createState() => _FingerprintAppState();
}
class _FingerprintAppState extends State<FingerprintApp> {
LocalAuthentication auth = LocalAuthentication();
late bool _canCheckBiometric;
late List<BiometricType> _availableBiometrics; // this list will store all types
//of biometric sensor like face, finger...
String autherized = "Not autherized"; // this String will check if we can
//access our app or not
// Now, create the function that will allow uus to check our biometric sensors
Future<void> _checkBiometric() async{
bool canCheckBiometric;
try{
canCheckBiometric = await auth.canCheckBiometrics;
} on PlatformException catch(e) {
print(e);
}
if(!mounted) return;
setState(() {
_canCheckBiometric = _canCheckBiometric;
});
}
//now that we checked if we are allowed to check our biometric lets get
// the availanle biometrics sensor on our device
Future<void > _getAvailableBiometrics() async{
List<BiometricType> availableBiometric;
try{
availableBiometric = await auth.getAvailableBiometrics();
} on PlatformException catch(e) {
print(e);
}
if(!mounted) return;
setState(() {
_availableBiometrics = availableBiometric;
});
}
Future<void> _authenticate() async {
bool authenticated = false;
try{
authenticated = await auth.authenticateWithBiometrics(
localizedReason: "Scan your finger to authentie",
useErrorDialogs: true,
stickAuth: false
);
}on PlatformException catch(e) {
print(e);
}
if(!mounted) return;
setState(() {
//here we can add what our app will do if the user authenticated first
autherized = authenticated ? "Autherized success" : "Failed to authenticate";
if(authenticated) {
Navigator.push(context, MaterialPageRoute(builder: (context) => SecondPage()));
}
print(autherized);
// note that you must configure your device and add a finger print
});
}
//before we test our app we should first initate the state and call
// our tow first function
@override
void initState() {
//TOdo: implement initstate
_checkBiometric();
_getAvailableBiometrics();
}
@override
Widget build(BuildContext context) {
return SafeArea(
child: Scaffold(
backgroundColor: Color(0xfFF3C3E52),
body: Padding(
padding: const EdgeInsets.symmetric(vertical: 12.0, horizontal: 24.0),
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Center(
child: Text("Login,", style: TextStyle(
color: Colors.white,
fontSize: 48.0,
fontWeight: FontWeight.bold
),),
),
Container(
margin: EdgeInsets.symmetric(vertical: 50.0),
child: Column(
children: <Widget>[
Image.asset(
'assets/fingerprint.webp',
width: 120.0,
),
Text("FingerPrint auth", style: TextStyle(
color: Colors.white,
fontSize: 22.0,
fontWeight: FontWeight.bold,
),),
Container(
width: 150.0,
child: Text("Authenticate using your fingerprint instead of your password",
textAlign: TextAlign.center,
style: TextStyle(
color: Colors.white,
height: 1.5
),
),
),
Container(
width: double.infinity,
child: ElevatedButton(
onPressed: _authenticate,
elevation: 0.0,
color: Color(0xFfF04A5ED),
shape: RoundedRectangleBorder(
borderRadius: BorderRadius.circular(30.0),
),
child: Padding(
padding: EdgeInsets.symmetric(vertical: 14.0, horizontal: 24.0),
child: Text("Autentic", style: TextStyle(
color: Colors.white,
),),
),
),
)
],
),
)
],
),
)
)
);
}
}