Log Apollo iOS Client GraphQL query variables and url to console?

Question

I would like to print the url of my Apollo iOS Client GraphQL queries to the Xcode console when the query is called.

Answer 1

Per the Apollo iOS Client docs, a logging interceptor can be added in a custom Interceptor Provider.

I created a custom interceptor provider using the code from DefaultInterceptorProvider, and included the logging interceptor.

import Apollo    

class InterceptorProviderWithLogging: InterceptorProvider {

  private let client: URLSessionClient
  private let store: ApolloStore
  private let shouldInvalidateClientOnDeinit: Bool

  public init(client: URLSessionClient = URLSessionClient(),
          shouldInvalidateClientOnDeinit: Bool = true,
          store: ApolloStore) {
    self.client = client
    self.shouldInvalidateClientOnDeinit = shouldInvalidateClientOnDeinit
    self.store = store
  }

  deinit {
    if self.shouldInvalidateClientOnDeinit {
      self.client.invalidate()
    }
  }

  open func interceptors<Operation: GraphQLOperation>(for operation: Operation) -> [ApolloInterceptor] {
    return [
      MaxRetryInterceptor(),
      CacheReadInterceptor(store: self.store),
      RequestLoggingInterceptor(),        // added logging interceptor
      NetworkFetchInterceptor(client: self.client),
      ResponseCodeInterceptor(),
      JSONResponseParsingInterceptor(cacheKeyForObject: self.store.cacheKeyForObject),
      AutomaticPersistedQueryInterceptor(),
      CacheWriteInterceptor(store: self.store),
    ]
  }

  open func additionalErrorInterceptor<Operation: GraphQLOperation>(for operation: Operation) -> ApolloErrorInterceptor? {
    return nil
  }
}

class RequestLoggingInterceptor: ApolloInterceptor {

  func interceptAsync<Operation: GraphQLOperation>(
    chain: RequestChain,
    request: HTTPRequest<Operation>,
    response: HTTPResponse<Operation>?,
    completion: @escaping (Result<GraphQLResult<Operation.Data>, Error>) -> Void) {
                
    if let url = try? request.toURLRequest().url?.absoluteString.removingPercentEncoding {
        if let variables = request.operation.variables {
            print("\(request.operation.operationName) parameters: \(variables) \(url)")
        } else {
            print("\(request.operation.operationName) \(url)")
        }
    }
    
    chain.proceedAsync(request: request, response: response, completion: completion)
  }
}

I use the custom interceptor provider in the Request Chain Network Transport.

private(set) lazy var apolloClient: ApolloClient = {

  let store = ApolloStore()
  let interceptorProvider = InterceptorProviderWithLogging(store: store)

  let requestChainTransport = RequestChainNetworkTransport(
    interceptorProvider: interceptorProvider,
    endpointURL: url,
    additionalHeaders: [:],
    autoPersistQueries: false,
    requestBodyCreator: ApolloRequestBodyCreator(),
    useGETForQueries: true,
    useGETForPersistedQueryRetry: false
  )

  return ApolloClient(networkTransport: requestChainTransport, store: store)
}()