Swift: using UIDatePicker as UITextField inputView not updating

Your handleDatePicker method is instantiating a new DatePicker each time it's called. You need to add a parameter to the function to pass in the sender (the DatePicker created in func dp)

@IBAction func dp(_ sender: UITextField) {
    let datePickerView = UIDatePicker()
    datePickerView.datePickerMode = .date
    sender.inputView = datePickerView
    datePickerView.addTarget(self, action: #selector(handleDatePicker(sender:)), for: .valueChanged)
}

@objc func handleDatePicker(sender: UIDatePicker) {
    let dateFormatter = DateFormatter()
    dateFormatter.dateFormat = "dd MMM yyyy"
    textfieldjobdate.text = dateFormatter.string(from: sender.date)
}