dispatch_async(dispatch_get_main_queue(), ^{
    self.myDatePicker.countDownDuration = (NSTimeInterval) aNewDuration ;
});

// Value Changed Event is not firing if minimum value hit
dispatch_after(dispatch_time(DISPATCH_TIME_NOW, 0.3 * NSEC_PER_SEC), dispatch_get_main_queue(), ^{
    [self.myDatePicker setCountDownDuration: self.myDatePicker.countDownDuration];
});

picker.countDownDuration = NSTimeInterval

picker.setDate(NSDate, animated: true)

override func viewDidLoad() {
    super.viewDidLoad()
    picker.setDate(setDateFromSeconds(seconds), animated: true)
}

func setDateFromSeconds(seconds: Double) -> (NSDate) {
    let intSeconds = Int(seconds)
    let minutes = (intSeconds / 60) % 60
    let hours = intSeconds / 3600
    let dateString = NSString(format: "%0.2d:%0.2d", hours, minutes)

    let dateFormatter = NSDateFormatter()
    dateFormatter.dateFormat = "hh:mm"
    return dateFormatter.dateFromString(dateString as String) as NSDate!
}

DispatchQueue.main.async(execute: {
    yourPicker.countDownDuration = TimeInterval()
})

@IBOutlet weak var fromPickerView: UIDatePicker!


@objc func toPickerViewDateChanged() {
        fromPickerView.minimumDate = toPickerView.date
    }
    override func viewDidLoad() {
        super.viewDidLoad()



toPickerView.backgroundColor = UIColor.white
    toPickerView.tintColor = .black
    toPickerView.maximumDate = Date()
    toPickerView.addTarget(self, action:
    #selector(toPickerViewDateChanged), for: UIControlEvents.valueChanged)