Network.swift

import Foundation
import Apollo

class Network {
    static let shared = Network()
    let apollo: ApolloClient = {
        let configuration = URLSessionConfiguration.default
        configuration.httpAdditionalHeaders = [
            "x-api-key": "<YOUR-API-KEY>"
        ]

        let url = URL(string: "<YOUR-GRAPHQL-ENDPOINT>")!

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