xcode - Limiting UIDatePicker dates from a particular time. Such as Input DOB to a restricted age limit

Question

In my code, I have a UITextField that when the user taps on opens a UIDatePicker to enable the user to easily and efficiently scroll through to their Date Of Birth. Obviously, we wouldn't want the UIDatePicker to scroll up to 2015 and over as it currently does. As it's a Date Of Birth entry field, i would also need to be able to limit entries to 16years+. How do i do this?

class SignUpViewController: UIViewController, UITextFieldDelegate {

    var datePicker:UIDatePicker!

    @IBOutlet weak var dateTextField: UITextField!

    override func viewDidLoad() {
        super.viewDidLoad()

        // UI DATE PICKER SETUP

        var customView:UIView = UIView(frame: CGRectMake(0, 100, 320, 160))
        customView.backgroundColor = UIColor.clearColor()

        datePicker = UIDatePicker(frame: CGRectMake(0, 0, 320, 160))
        datePicker.datePickerMode = UIDatePickerMode.Date

        customView.addSubview(datePicker)
        dateTextField.inputView = customView
        var doneButton:UIButton = UIButton (frame: CGRectMake(100, 100, 100, 44))
        doneButton.setTitle("Done", forState: UIControlState.Normal)
        doneButton.addTarget(self, action: "datePickerSelected", forControlEvents: UIControlEvents.TouchUpInside)
        doneButton.backgroundColor = UIColor .grayColor()
        dateTextField.inputAccessoryView = doneButton

Answer 1

You can use dateByAddingUnit and subtract 16 years from current date to set the maximum date for your datePicker as follow:

datePicker.maximumDate = NSCalendar.currentCalendar().dateByAddingUnit(.Year, value: -16, toDate: NSDate(), options: [])

Xcode 10.2.1 ? Swift 5

datePicker.maximumDate = Calendar.current.date(byAdding: .year, value: -16, to: Date())