Swift倒计时功能

import UIKit

class CountdownViewController: UIViewController {
    @IBOutlet weak var countdownLabel: UILabel!
    
    var timer: Timer?
    var countdownSeconds = 60
    
    override func viewDidLoad() {
        super.viewDidLoad()
        startCountdown()
    }
    
    func startCountdown() {
        timer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(updateCountdown), userInfo: nil, repeats: true)
    }
    
    @objc func updateCountdown() {
        if countdownSeconds > 0 {
            countdownSeconds -= 1
            countdownLabel.text = formatTime(countdownSeconds)
        } else {
            timer?.invalidate()
            // 倒计时结束后的处理逻辑
        }
    }
    
    func formatTime(_ seconds: Int) -> String {
        let hours = seconds / 3600
        let minutes = (seconds % 3600) / 60
        let seconds = (seconds % 3600) % 60
        
        return String(format: "%02d:%02d:%02d", hours, minutes, seconds)
    }
}