initialization.md

title
Creating a client

In most cases, you'll want to create a single shared instance of ApolloClient and point it at your GraphQL server. The easiest way to do this is to define a global variable in AppDelegate.swift:

let apollo = ApolloClient(url: URL(string: "http://localhost:8080/graphql")!)

Adding additional headers

If you need to add additional headers to requests, to include authentication details for example, you can create your own URLSessionConfiguration and use this to configure an HTTPNetworkTransport. If you want to define the client as a global variable, you can use an immediately invoked closure here:

let apollo: ApolloClient = {
  let configuration = URLSessionConfiguration.default
  // Add additional headers as needed
  configuration.httpAdditionalHeaders = ["Authorization": "Bearer <token>"]

  let url = URL(string: "http://localhost:8080/graphql")!

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

Right now, additional headers can only be specified when creating a client. We're working on a better solution for dynamic configuration of the network transport, including the ability to retry requests that failed after refreshing an access token. Please chime in on apollographql/apollo-ios#37 to help shape the design of this feature or to contribute to it.