## Hook for Signing In a User

Connects to the relay server, generates a sign in link to present to the user, and polls the relay server for the user’s Farcaster wallet signature. If you want to build your own sign in component with a custom UI, use the `useSignIn` hook.

```javascript
import { useSignIn, QRCode } from '@farcaster/auth-kit';

function App() {
  const {
    signIn,
    url,
    data: { username },
  } = useSignIn({
    onSuccess: ({ fid }) => console.log('Your fid:', fid),
  });

return (
    <div>
      <button onClick={signIn}>Sign In</button>
      {url && (
        <span>
          Scan this: <QRCode uri={url} />
        </span>
      )}
      {username && `Hello, ${username}!`}
    </div>
  );
}
```

## Parameters

| Parameter       | Type      | Description                                              | Default                        |
|------------------|-----------|----------------------------------------------------------|--------------------------------|
| `timeout`        | `number`  | Return an error after polling for this long.            | `300_000` (5 minutes)          |
| `interval`       | `number`  | Poll the relay server for updates at this interval.     | `1500` (1.5 seconds)           |
| `nonce`          | `string`  | A random nonce to include in the Sign In With Farcaster message. | None                           |
| `notBefore`      | `string`  | Time when the SIWF message becomes valid. ISO 8601 datetime string. | None                           |
| `expirationTime` | `string`  | Time when the SIWF message expires. ISO 8601 datetime string. | None                           |
| `requestId`      | `string`  | An optional system-specific ID to include in the SIWF message. | None                           |
| `onSuccess`      | `function`| Callback invoked when sign in is complete and the user is authenticated. | None                      |
| `onStatusResponse`| `function`| Callback invoked when the component receives a status update from the relay server. | None                     |
| `onError`        | `function`| Error callback function.                                | None                           |

## Returns

```javascript
{
  signIn: () => void;
  signOut: () => void;
  connect: () => void;
  reconnect: () => void;
  isConnected: boolean;
  isSuccess: boolean;
  isPolling: boolean;
  isError: boolean;
  error: AuthClientError;
  channelToken: string;
  url: string;
  appClient: AppClient;
  data: {
      state: "pending" | "complete";
      nonce: string;
      message: string;
      signature: Hex;
      fid: number;
      username: string;
      bio: string;
      displayName: string;
      pfpUrl: string;
      custody?: Hex;
      verifications?: Hex[];
  },
  validSignature: boolean;
};
```

| Parameter           | Description                                                                       |
|---------------------|-----------------------------------------------------------------------------------|
| `signIn`            | Call this function following `connect` to begin polling for a signature.         |
| `signOut`           | Call this function to clear the AuthKit state and sign out the user.             |
| `connect`           | Connect to the auth relay and create a channel.                                   |
| `reconnect`         | Reconnect to the relay and try again. Call this in the event of an error.        |
| `isConnected`       | True if AuthKit is connected to the relay server and has an active channel.      |
| `isSuccess`         | True when the relay server returns a valid signature.                             |
| `isPolling`         | True when the relay state is "pending" and the app is polling the relay server for a response. |
| `isError`           | True when an error has occurred.                                                  |
| `error`             | `AuthClientError` instance.                                                       |
| `channelToken`      | Connect relay channel token.                                                       |
| `url`               | Sign in With Farcaster URL to present to the user. Links to the Farcaster client in v1. |
| `appClient`         | Underlying `AppClient` instance.                                                  |
| `data.state`        | Status of the sign in request, either "pending" or "complete"                  |
| `data.nonce`       | Random nonce used in the SIWE message. If you don’t provide a custom nonce as an argument to the hook, you should read this value. |
| `data.message`     | The generated SIWE message.                                                       |
| `data.signature`    | Hex signature produced by the user’s Farcaster client app wallet.                |
| `data.fid`          | User’s Farcaster ID.                                                             |
| `data.username`     | User’s Farcaster username.                                                        |
| `data.bio`         | User’s Farcaster bio.                                                             |
| `data.displayName`  | User’s Farcaster display name.                                                    |
| `data.pfpUrl`      | User’s Farcaster profile picture URL.                                             |
| `data.custody`     | User’s FID custody address.                                                       |
| `data.verifications` | List of user’s verified addresses.                                               |
| `validSignature`    | True when the signature returned by the relay server is valid.                   |