Once you've setup an Auth API for your application, you can add Auth support to your React Native apps.

To add support for Auth to your React Native apps, you'll first need to setup your React Native app.

Now we'll need to wrap our app with the ThirdwebProvider which stores the necessary context for Auth, and we'll provide some configuration with the authConfig option so that our app knows how to communicate with our Auth API.

import { ThirdwebProvider } from "@thirdweb-dev/react-native";

export default function MyApp({ Component }) {
  return (
    <ThirdwebProvider
      // Required configuration for the provider, but doesn't affect Auth.
      activeChain="ethereum"
      clientId="your-client-id"
      authConfig={{
        // Set this to your domain to prevent phishing attacks
        domain: "example.com",
        // The URL of your Auth API
        authUrl: "/api/auth",
        // (optional) Secure storage to use for storing the auth token when using JWT tokens.
        secureStorage: new SecureStorage(),
      }}
    >
      <AppInner />
    </ThirdwebProvider>
  );
}

Note that in React Native auth works with JWT tokens since cookie management is not well supported. For this reason you can pass a secureStorage prop for us to store the JWT for you, if not, it will default to using expo-secure-store

The simplest way to add an Auth flow to our app is to use the ConnectWallet button. This button prompts the user to connect to the supportedWallets specified in the ThirdwebProvider. Once connected to a wallet you can call login to authenticate.

The login function returns the JWT token which you can use in subsequent requests to your backend.

import { ConnectWallet, useLogin } from "@thirdweb-dev/react-native";

export default function AppInner() {
  const { login } = useLogin();

  return (
    <>
      <ConnectWallet />;
      <Button
        title="Login"
        onPress={() => {
          const token = login();
        }}
      />
    </>
  );
}

For a more customized setup with custom UI or logic, we can instead use the wallet connection and Auth hooks provided by the @thirdweb-dev/react-native package.

import {
  useAddress,
  useMetamask,
  useLogin,
  useLogout,
  useUser,
} from "@thirdweb-dev/react-native";

export default function AppInner() {
  const address = useAddress();
  const connect = useMetaMaskWallet();
  const { login } = useLogin();
  const { logout } = useLogout();
  const { user, isLoggedIn } = useUser();

  return (
    <>
      {isLoggedIn ? (
        <Button title="Logout" onPress={() => logout()} />
      ) : address ? (
        <Button title="Login" onPress={() => login()} />
      ) : (
        <Button title="Connect" onPress={() => connect()} />
      )}

      <Text>Connected Wallet: {address}</Text>
      <Text>User: {user?.address || "N/A"}</Text>
    </>
  );
}

Here, we use the useMetaMaskWallet hook to prompt our users to connect their metamask wallets, and then we use the useLogin hook to login to our app with Auth. Then, we can access and display the logged in user with the useUser hook, and we can logout the user with the useLogout hook.

For a full list of wallet connection hooks, check out our React Native SDK documentation.

On your app, you may want to check whether or not the user is logged in to conditionally render certain parts of your app. You can do this with the isLoggedIn value from the useUser hook:

import { useUser } from "@thirdweb-dev/react-native";

export default function AppInner() {
  const { isLoggedIn } = useUser();

  return (
    <>
      {isLoggedIn ? (
        <Text>Here's some content only visible to logged in users.</Text>
      ) : (
        <Text>Here's some content only visible to logged out users.</Text>
      )}
    </>
  );
}

Once a user is logged in, you can access their user data and session data with the useUser hook. The user value will be null if the user is not logged in, but once they're logged in, it will contain the address of the logged in user, the session context set by the backend on login, and any extra user-associated data sent by the backend.

import { useUser } from "@thirdweb-dev/react-native";

export default function AppInner() {
  const { user } = useUser();

  return (
    <>
      <Text>Logged in user: {user?.address}</Text>
      <Text>Session context: {user?.context}</Text>
      <Text>Extra user data: {user?.data}</Text>
    </>
  );
}

You can think of user.context as a way for the backend to store arbitrary session data on the JWT, like a user's role or permissions. This data is then accessible on the frontend and doesn't change until a user has to login again.

Meanwhile, user.data is a way for the backend to send the client any data associated with the current user like their name, profile picture, and other information. Since this data isn't stored on the JWT, it can change at any time.

When using the useUser hook, you may want to show a loading state while the user's session is being fetched from the backend. You can do this by checking the isLoading value from the hook:

import { useUser } from "@thirdweb-dev/react-native";

export default function AppInner() {
  const { user, isLoading } = useUser();

  return (
    <>
      {isLoading ? (
        <Text>Loading...</Text>
      ) : (
        <Text>Logged in user: {user?.address}</Text>
      )}
    </>
  );
}

Similarly, the useLogin and useLogout hooks also have loading states to indicate when a request to the backend is being made.

import { useLogin, useLogout } from "@thirdweb-dev/react-native";

export default function AppInner() {
  const { login, isLoading: isLoggingIn } = useLogin();
  const { logout, isLoading: isLoggingOut } = useLogout();

  return (
    <>
      {isLoggingIn ? (
        <Text>Logging in...</Text>
      ) : (
        <Button title="Login" onPress={() => login()} />
      )}
      {isLoggingOut ? (
        <Text>Logging out...</Text>
      ) : (
        <Button title="Logout" onPress={() => logout()} />
      )}
    </>
  );
}

The login function automatically uses some default values for the necessary fields of the EIP4361/CAIP122 specifications.

However, if you want full access to customize these field values, you can overwrite them by passing an object to the login function:

import { useLogin } from "@thirdweb-dev/react-native";

export default function AppInner() {
  const { login } = useLogin();

  async function handleLogin() {
    // All of these fields are optional
    login({
      uri: "https://example.com",
      statement: "Please agree to our terms of service!",
      chainId: "123",
      nonce: "123"
      version: "1",
      resources: ["https://tos.example.com"],
    })
  }

  return (
    <>
      <Button title="Login" onPress={() => handleLogin()} />
    </>
  );
}

Since logging in requires the user to sign a message, the login function is asynchronous and may throw an error if the user rejects the message. You can handle this error case by using a try/catch block:

import { useLogin } from "@thirdweb-dev/react-native";

export default function AppInner() {
  const { login } = useLogin();

  async function handleLogin() {
    try {
      await login();
    } catch (err) {
      console.error(err);
    }
  }

  return (
    <>
      <Button title="Login" onPress={() => handleLogin()} />
    </>
  );
}

Auth in React Native uses secure storage to store the JWT token. This means that you need to pass this token in other calls to your backend.

You should get the token after logging in and pass it down as a header in subsequent network calls.

export default function AppInner() {
  const { login } = useLogin();
  const [authToken, setAuthToken] = useState<string | null>(null);

  const getSecret = useCallback(async () => {
    let res;
    try {
      res = await fetch(`${your - domain}/api/data`, {
        headers: {
          Authorization: `Bearer ${authToken}`,
        },
      });
    } catch (error) {
      console.log("error", error);
      return;
    }

    const data = await res.json();
  }, [authToken]);

  return (
    <>
      <Button
        title="Login"
        onPress={async () => {
          const token = await login();
          setAuthToken(token);
        }}
      />
      <Button title="Get Secret" onPress={getSecret} />
    </>
  );
}

As discussed in the switching accounts section of the Auth API explanation, Auth enables multiple wallets to login at once. If you use the thirdweb React SDK on the frontend to enable users to connect their wallets via the wallet connection hooks or the <ConnectWallet/> button, switching accounts will be automatically handled for your users when they switch connected wallets. However, if you want to customize when accounts or switched or add your own manual account switching flows, you can use the useSwitchAccount hook exposed by the React SDK.

import { useSwitchAccount } from "@thirdweb-dev/react";

export default function Home() {
  const { switchAccount } = useSwitchAccount();

  async function handleSwitchAccount() {
    // The wallet address to switch accounts to (assuming the user has logged in previously)
    const newWalletAddress = "0x...";
    await switchAccount(newWalletAddress);
  }

  return (
    <div>
      <button onClick={handleSwitchAccount}>Switch Accounts</button>
    </div>
  );
}