LowDataModeURLSessionConfig.swift

func expensiveLongRunningDataTask() {
    let config = URLSessionConfiguration.default

    // Be low data mode compliant
    config.allowsConstrainedNetworkAccess = false

    // Automatically retrigger the request when we are on Wi-Fi.
    config.waitsForConnectivity = true

    let request = URLRequest(url: myURL)

    let session = URLSession(configuration: config, delegate: nil, delegateQueue: nil)
    session.dataTask(with: request) { data, response, error in

        // Logic...

    }.resume()
}