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.

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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. 
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.

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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. 
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)

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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. 
import SwiftGraphQLClient

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