class ViewController: UIViewController {

    override func viewDidLoad() { super.viewDidLoad() }
    override func didReceiveMemoryWarning() { super.didReceiveMemoryWarning() }

    override func viewDidAppear(_ animated: Bool) {

        // Logic here to load saved data to text field.

        resumeSaving()
    }

    func resumeSaving() {
         Timer.scheduledTimer(
             timeInterval: 4,
             target: self,
             selector: #selector(saveText),
             userInfo: nil,
             repeats: true)
    }


    @objc func saveText() {

        // Logic here to save data in text field.

        print("DATA SAVED.")
    }

}