iOS UIDatePicker in UIDatePickerMode.countDownTimer value changed bug

ViewController.swift

import UIKit

class ViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        
        // Create a DatePicker
        let datePicker: UIDatePicker = UIDatePicker()
        
        // Posiiton date picket within a view
        datePicker.frame = CGRect(x: 10, y: 50, width: self.view.frame.width, height: 200)
        
        // Set some of UIDatePicker properties
        datePicker.backgroundColor = UIColor.white
        datePicker.datePickerMode = UIDatePickerMode.countDownTimer;
        
        // Add an event to call onDidChangeDate function when value is changed.
        datePicker.addTarget(self, action: #selector(ViewController.datePickerValueChanged(_:)), for: .valueChanged)
        
        // Add DataPicker to the view
        self.view.addSubview(datePicker)
        
    }
    
    // Not called the first time
    func datePickerValueChanged(_ sender: UIDatePicker){
        print("Selected value \(sender.countDownDuration)")
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }


}

Just reported to Apple.

It's 2021. Bug still there...

The only way I found to work around it is to start a timer in viewDidLoad, that calls datePickerValueChanged, and invalidate the timer once the sender is not nil.

Something like:

// Optional sender, so we can call it ourselves
func datePickerValueChanged(_ sender: UIDatePicker?) {
    let selectedValue: TimeInterval
    
    if let sender = sender {
        // Called by UIKit, UIDatePicker works, we no longer need the timer
        timer.invalidate()
        selectedValue = sender.countDownDuration
   } else {
       // Called by the timer, read the current value of the datePicker, because it's accurate, only the `.valueChanged` event is not fired
       selectedValue = datePicker.countDownDuration
   }
   
    print("Selected value \(sender.countDownDuration)")
}

func viewDidLoad() {
        // Set a very small interval, so we read the value often, in case the screen closes for example
        self.timer = Timer.scheduledTimer(withTimeInterval: 0.01, repeats: true, block: { [weak self] _ in
            self?.datePickerValueChanged(nil)
        })
}

Thanks @lordzsolt , your solution is working.

It is weird this bug is still alive 👎