swift not updating textfield.text using UIDatePicker

Xcode 9 • Swift 4

@objc func handleDatePicker(_ datePicker: UIDatePicker) {
    textField3.text = datePicker.date.formatted
}

override func viewDidLoad() {
    super.viewDidLoad()
    datePicker.addTarget(self, action: #selector(handleDatePicker), forControlEvents: .valueChanged)
}

---

extension Date {
    static let formatter: DateFormatter = {
        let formatter = DateFormatter()
        formatter.dateFormat = "EEEE, dd MMM yyyy HH:mm:ss Z"
        return formatter
    }()
    var formatted: String {
        return Date.formatter.string(from: self)
    }
}

Swift 3 version of @Leo Dabus answer:

func handleDatePicker(sender: UIDatePicker) {
        textField3.text = datePicker.date.formatted
    }

override func viewDidLoad() {
    super.viewDidLoad()
    datePicker.addTarget(self, action: #selector(handleDatePicker(sender:)), for: UIControlEvents.valueChanged)
}

extension Date {
    var formatted: String {
        let formatter = DateFormatter()
        formatter.dateFormat = "EEEE, dd MMM yyyy HH:mm:ss Z"
        return  formatter.string(from: self as Date)
    }
}