iPhone-动态更新NSDate的时钟？

import UIKit

class ViewController: UIViewController {
    @IBOutlet weak var clockLabel: UILabel!
    var timer: Timer?
    
    override func viewDidLoad() {
        super.viewDidLoad()
        startClock()
    }
    
    func startClock() {
        timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(updateClock), userInfo: nil, repeats: true)
        timer?.fire()
    }
    
    @objc func updateClock() {
        let currentDate = Date()
        let dateFormatter = DateFormatter()
        dateFormatter.dateFormat = "HH:mm:ss"
        let formattedDate = dateFormatter.string(from: currentDate)
        clockLabel.text = formattedDate
    }
    
    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)
        timer?.invalidate()
    }
}