How to Autofill OTP Code from SMS in Flutter

**How to Autofill OTP Code from SMS in Flutter: A Step-by-Step Guide**

Hey there, fellow Flutter developers! Are you tired of manually entering One-Time Passwords (OTPs) every time you receive one? Well, you’re in luck! In this post, we’ll show you how to autofill OTP codes from SMS in your Flutter app using a simple and elegant solution.

**The Problem**

We’ve all been there – waiting for that precious OTP to arrive in an SMS and then typing it in manually, only to realize that we’ve mistyped it and need to wait again. It’s frustrating, to say the least. But fear not, dear developers, for we have a solution that will save you and your users from this tedious process.

**The Solution**

To autofill OTP codes from SMS in Flutter, we’ll use the `flutter_sms` package, which provides a simple and easy-to-use interface for sending and receiving SMS messages. We’ll also use the `flutter_verification_code` package to generate a verification code and verify it with the user.

Here’s the step-by-step process:

**Step 1: Add the Packages to Your Project**

In your Flutter project, add the following packages to your `pubspec.yaml` file:

“`yaml
dependencies:
flutter_sms: ^1.0.7
flutter_verification_code: ^2.0.0
“`

Then, run `pub get` or `flutter pub get` to get the packages installed.

**Step 2: Request SMS Permission**

Before we can receive SMS messages, we need to request permission to access the device’s SMS storage. Add the following code to your `MainActivity.java` file (Kotlin for Android):

“`java
import android.os.Bundle;
import android.telephony.SmsManager;

public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Request SMS permission
SmsManager.setDefaultSmsServicePackage(“com.android.messaging”);
}
}
“`

**Step 3: Receive SMS Message**

Now that we have the permission to access the SMS storage, we can receive SMS messages using the `flutter_sms` package. Add the following code to your Flutter app:

“`dart
import ‘package:flutter/material.dart’;
import ‘package:flutter_sms/flutter_sms.dart’;

class OTPScreen extends StatefulWidget {
@override
_OTPScreenState createState() => _OTPScreenState();
}

class _OTPScreenState extends State {
List _otpList = [];
bool _otpVerified = false;

@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(‘OTP Screen’),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Text(
‘Enter OTP:’,
style: TextStyle(fontSize: 24),
),
SizedBox(height: 20),
TextField(
readOnly: _otpVerified,
enabled: !_otpVerified,
decoration: InputDecoration(
border: OutlineInputBorder(),
),
onChanged: (value) {
if (value.length == 6) {
_otpList.add(value);
}
},
),
SizedBox(height: 20),
ElevatedButton(
onPressed: () async {
// Check if OTP is verified
if (_otpList.length > 0 && _otpVerified) {
// Verify OTP
final otpCode = _otpList[0];
// Verify OTP with server (not shown)
if (verifyOtp(otpCode)) {
setState(() {
_otpVerified = true;
});
} else {
// Show error message
ScaffoldMessenger.of(context).showSnackBar(
SnackBar(content: Text(‘Invalid OTP’)),
);
}
}
},
child: Text(‘Verify OTP’),
),
],
),
),
);
}
}
“`

**Step 4: Handle SMS Message**

Now that we’ve set up the UI, let’s handle the SMS message. We’ll use the `flutter_sms` package to receive SMS messages and verify them with the user. Add the following code to your Flutter app:

“`dart
import ‘package:flutter/material.dart’;
import ‘package:flutter_sms/flutter_sms.dart’;

class OTPScreen extends StatefulWidget {
@override
_OTPScreenState createState() => _OTPScreenState();
}

class _OTPScreenState extends State {
// … existing code …

@override
void initState() {
super.initState();
_receiveSmsMessage();
}

void _receiveSmsMessage() {
SmsMessage smsMessage = SmsMessage(SmsMessage.SMS_INBOX);
if (smsMessage != null) {
// Get the SMS message
String message = smsMessage.getMessageBody();
// Verify the SMS message
if (verifySmsMessage(message)) {
// Show the OTP in the UI
setState(() {
_otpList.add(message.replaceFirst(‘OTP:’, ”));
});
}
}
}
}
“`

**And There You Have It!**

That’s it! With these simple steps, you’ve successfully implemented autofill OTP code from SMS in your Flutter app. No more tedious typing for you and your users.

Remember to verify the SMS message and OTP code with your server to ensure it’s valid and legitimate. Happy coding!