Integrating Solana Mobile Wallet Adapter

npm install @solana-mobile/mobile-wallet-adapter-protocol-web3js @solana-mobile/mobile-wallet-adapter-protocol

import {transact} from '@solana-mobile/mobile-wallet-adapter-protocol-web3js';
import {useLoginWithSiws} from '@privy-io/expo';
import {toByteArray} from 'react-native-quick-base64';
import {PublicKey} from '@solana/web3.js';
import {Buffer} from 'buffer';

const MwaLoginButton = () => {
  const {generateMessage, login} = useLoginWithSiws();

  const handleLogin = async () => {
    try {
      await transact(async (wallet) => {
        // 1. Create a MWA session
        const authorizationResult = await wallet.authorize({
          chain: 'mainnet-beta',
          identity: {
            name: 'My app',
            uri: 'https://myapp.io',
            icon: 'https://myapp.io/icon.png'
          }
        });
        const desiredAccount = authorizationResult.accounts[0];

        // 2. Convert base64 address to base58 (Privy expects base58)
        const addressBytes = toByteArray(desiredAccount.address);
        const publicKey = new PublicKey(addressBytes);
        const base58Address = publicKey.toBase58();

        // 3. Generate a Privy SIWS message for the wallet address
        const siwsMessage = await generateMessage({
          wallet: {address: base58Address}, // Use base58 for Privy
          from: {domain: 'com.myapp.app', uri: 'https://myapp.io'}
        });

        // 4. Convert the SIWS message to Uint8Array for signing
        const encodedSiwsMessage = new TextEncoder().encode(siwsMessage.message);

        // 5. Request user to sign the SIWS message with their wallet
        const [signatureBytes] = await wallet.signMessages({
          addresses: [desiredAccount.address], // Use base64 for MWA
          payloads: [encodedSiwsMessage]
        });
        const signatureBase64 = Buffer.from(signatureBytes).toString('base64');

        // 6. Authenticate with Privy using the signed message
        const user = await login({
          signature: signatureBase64,
          message: siwsMessage.message
        });

        return {mwaResult: authResult, user};
      });
    } catch (error) {
      console.error('Login failed', error);
    }
  };

  return <Button title="Login with MWA" onPress={handleLogin} />;
};