Asynchronous Networking

DispatchQueue.global().async {
    let data = Data(contentsOf: url)
    DispatchQueue.main.async {
        // Update UI
    }
}

• There is no way to cancel this synchronous network call of Data

DispatchQueue.global().async {
    let url = URL(string: "")!
    let task = URLSession.shared.dataTask(with: url, completionHandler: { (data, response, error) in
        DispatchQueue.main.async {
            // Update UI
        }
    })
    task.resume()
}