Flutter (Mobile)

The Capsule SDK for Flutter allows you to easily integrate secure and scalable wallet functionalities into your mobile applications. This guide covers the installation, setup, and usage of the Capsule SDK, including handling authentication flows.

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Prerequisites

To use Capsule, you need an API key. This key authenticates your requests to Capsule services and is essential for integration.

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Dependency Installation

To install the Capsule SDK and required dependencies, use the following command:

flutter pub add capsule

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Project Setup

To set up associated domains for passkey functionality in your Flutter project, you need to configure both iOS and Android platforms:

• iOS
• Android

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Using the Capsule SDK

The Capsule SDK provides two main authentication flows: creating a new user and logging in an existing user. Both flows utilize passkeys for secure and seamless authentication. Follow the steps below to implement these flows in your Flutter application.

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Capsule Initialization

First, initialize the Capsule SDK within your application. This step is crucial for setting up the necessary environment.

import 'package:capsule/capsule.dart';
import 'package:flutter_dotenv/flutter_dotenv.dart';

late Capsule _capsule;

void initCapsule() {
  _capsule = Capsule(environment: Environment.beta, apiKey: dotenv.env['CAPSULE_API_KEY']!);
  _capsule.init();
}

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Create New User

This flow guides you through the process of registering a new user, verifying their email, and setting up their wallet. The steps below should be executed sequentially within the same function or flow.

bool userExists;
try {
  userExists = await _capsule.checkIfUserExists(email);
} catch (e) {
  print("Error checking user existence: \$e");
  return;
}

if (userExists) {
  print("User already exists. Please use passkey login.");
  return;
}

try {
  await _capsule.createUser(email);
  print("User created. Verification email sent.");
} catch (e) {
  print("Error creating user: \$e");
  return;
}

String? biometricsId;
try {
  biometricsId = await _capsule.verifyEmail(verificationCode);
  print("Email verified successfully");
} catch (e) {
  print("Error verifying email: \$e");
  return;
}

if (biometricsId == null) {
  print("Verification failed. Please try again.");
  return;
}

try {
  await _capsule.generatePasskey(email, biometricsId);
  print("Passkey generated successfully");
} catch (e) {
  print("Error generating passkey: \$e");
  return;
}

try {
  final walletResult = await _capsule.createWallet(skipDistribute: false);
  final wallet = walletResult.wallet;
  print("Wallet created: \${wallet.address}");
  // Store or display the wallet.recoverySecret securely
} catch (e) {
  print("Error creating wallet: \$e");
  return;
}

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Login Existing User

This flow demonstrates how to authenticate an existing user using their email and passkey. The steps below should be executed sequentially to ensure proper authentication.

Wallet wallet;
try {
  wallet = await _capsule.login();
  print("User logged in successfully");
} catch (e) {
  print("Error during login: \$e");
  return;
}

// Handle wallet information after successful login
final address = wallet.address;
print("Wallet address: \$address");

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Examples

To help you get started with the Capsule Flutter SDK, we’ve prepared a comprehensive example:

This example repository demonstrates how to handle user authentication, wallet creation, and signing messages using the Capsule SDK in a Flutter application.

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Next Steps

After integrating Capsule, you can explore other features and integrations to enhance your Capsule experience. Here are some resources to help you get started:

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Ecosystems

Learn how to use Capsule with popular Web3 clients and wallet connectors. We’ll cover integration with key libraries for EVM, Solana, and Cosmos ecosystems.

If you’re ready to go live with your Capsule integration, make sure to review our go-live checklist:

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Troubleshooting

If you encounter issues during the integration or usage of the Capsule SDK in your Flutter application, here are some common problems and their solutions:

For more detailed troubleshooting and solutions specific to Flutter, please refer to our comprehensive troubleshooting guide:

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Support

If you’re experiencing issues that aren’t resolved by our troubleshooting resources, please contact our support team for assistance. To help us serve you better, include the following information in your support request:

1. 1

   A detailed description of the problem you’re encountering.

2. 2

   Any relevant error messages or logs.

3. 3

   Steps to reproduce the issue.

4. 4

   Details about your system or environment (e.g., device, operating system, software version).

Providing this information will enable our team to address your concerns more efficiently.