GraphQL Apollo iOS Client Response Headers

Question

I am using Apollo iOS client for doing GraphQL queries. I need to pass Auth token in the header which I am able to achieve using below code -

let apolloAuth: ApolloClient = {
            let configuration = URLSessionConfiguration.default
            let token = "Bearer \(UserDefaults.standard.string(forKey: "UserToken") ?? "")"
            // Add additional headers as needed
            configuration.httpAdditionalHeaders = ["Authorization": token]

            let url = URL(string: "...URL.../graphql")!

            return ApolloClient(networkTransport: HTTPNetworkTransport(url: url, configuration: configuration))
        }()

My fetch query goes as below -

apolloAuth.fetch(query: referralQuery){ (result, error) in

        if let error = error {
            print(error.localizedDescription)
            return
        }else{
            self.referralId = result?.data?.referrals?.id
        }

    }

Now my Server returns a refreshed auth token after every request which is a part of response header. I need to get the token from the response header but I am unable to find out a way to do that. Can someone guide me on this.

Answer 1

Use interceptors for reading the tokens from the response header.

Sample code:

class UserManagementInterceptor: ApolloInterceptor {

    /// Helper function to add the token then move on to the next step
    private func addTokenAndProceed<Operation: GraphQLOperation>(
        to request: HTTPRequest<Operation>,
        chain: RequestChain,
        response: HTTPResponse<Operation>?,
        completion: @escaping (Result<GraphQLResult<Operation.Data>, Error>) -> Void) {
            
            if let headerFields = response?.httpResponse.allHeaderFields {
                // Read the required tokens
            }
            
            chain.proceedAsync(request: request,
                               response: response,
                               completion: completion)
        }
    
    func interceptAsync<Operation: GraphQLOperation>(
        chain: RequestChain,
        request: HTTPRequest<Operation>,
        response: HTTPResponse<Operation>?,
        completion: @escaping (Result<GraphQLResult<Operation.Data>, Error>) -> Void) {
        addTokenAndProceed(to: request,
                           chain: chain,
                           response: response,
                           completion: completion)
        
    }
}

Reference: Creating a client

Answer 2

The URLSessionConfiguration object comes with a shared HTTPCookieStorage singleton object. Once you set the apollo client with that configuration, what you could do is store the auth token in a cookie using your server, then send the cookies to the client on every request. Automatically, you will be able to access that cookie like so:

apollo.fetch(query: GraphQLQuery()) { result, error in
        if let error = error { fatalError(error.localizedDescription) }
        if let data = result?.data {
          // do something with data
        }
        self.getCookies()
      }

func getCookies() {
    let cookies = HTTPCookieStorage.shared.cookies
    if let c = cookies {
      print(c)
      // if your server sent a token inside a cookie, you will see it here
    }
  }