Swift Post Concurrency Blog Post Code Example

Concurrency2.swift

/* I put the first DispatchQueue method intentionally to indicate that we're on
   the background queue. Just to support the explanation for beginner developers
This is not necessary in real-life, URLSession is thread-safe. Whenever you call URLSession
   it'll start executing on background. */
DispatchQueue.global().async {
    let url = URL(string: "https://theswiftpost.co/")
    if let url = url {
        DispatchQueue.main.sync {
            showLoadingIndicator() // UI Operation; has to run on the main queue
        }
        let task = URLSession.shared.dataTask(with: url) { (data, response, error) in
            if error != nil {
                DispatchQueue.main.sync {
                    showErrorAlert(error) // UI operation; has to run on the main queue!!
                }
            } else if let data = data {
                debugPrint(usableData) //JSONSerialization
            }
            debugPrint(“Completed”)
        }
        task.resume()
    }
}