> ## Documentation Index
> Fetch the complete documentation index at: https://swift-graphql.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Authentication

This guide shows how you possible ways to make an authenticated GraphQL requests using SwiftGraphQL client.

> You can see the full code in practice in `thesocialnetwork` example on [GitHub](https://github.com/maticzav/).

### Using AuthExchange

SwiftGraphQLClient comes with a special exchange dedicated to authenticating your requests - `AuthExchange`. You provide a function that returns a token and it applies that token to a given header to make an authenticated request.

It's important that `AuthExchange` comes before `FetchExchange`, `WebSocketExchange` or any other exchange that transmits the data.

```swift theme={null}
import SwiftGraphQLClient

let client = SwiftGraphQLClient.Client(
	request: http,
  exchanges: [
		AuthExchange(header: "Authentication", getToken: {
				if let token = AuthClient.getToken() {
						return "Bearer \(token)"
				}
				return nil
		}),
		FetchExchange(),
	]
)
```

Since the `getToken` function is not asynchronous, we recommend that you first load the token from storage and store it as a statically available variable.

> You can find the full example in `thesocialnetwork` example on [GitHub](https://github.com/maticzav).

### Modifying URLRequest

Instead of using an exchange, you can also modify the URLRequest directly. This is useful if you want to add additional non-standard headers to the request.

```swift theme={null}
let client = SwiftGraphQLClient.Client(request: API_ENDPOINT)

let request = URLRequest(url: API_ENDPOINT)
request.setValue("Token ssssshhhhhh", forHTTPHeaderField: "Auth")

client.query(selection, request: request, policy: .networkOnly)
```

### Using ExtensionsExchange

`ExtensionsExchange` lets you add custom values to the `extension` field of a GraphQL query. Adding a custom authentication property to query extensions can be useful when you can't access request headers on the server (e.g. when using subscriptions).

`ExtensionsExchange` lets you specify a function that should be synchronously called for each request. The function should either return `nil` value when there are no extensions or an `AnyCodable` value containing additional request information.

```swift theme={null}
import SwiftGraphQLClient

let client = SwiftGraphQLClient.Client(
	request: http,
  exchanges: [
		ExtensionsExchange(getExtensions: {
				if let token = AuthClient.getToken() {
						return ["headers": ["Authentication": "Bearer \(token)"]]
				}
				return nil
		}),
		FetchExchange(),
	]
)
```