使用NSTimer获得准确的计时

import UIKit

class ViewController: UIViewController {

    private var displayLink: CADisplayLink?
    private var startTime: CFTimeInterval = 0

    override func viewDidLoad() {
        super.viewDidLoad()

        startDisplayLink()
    }

    private func startDisplayLink() {
        displayLink = CADisplayLink(target: self, selector: #selector(updateTime))
        displayLink?.add(to: .main, forMode: .common)
        startTime = CACurrentMediaTime()
    }

    @objc private func updateTime() {
        let currentTime = CACurrentMediaTime()
        let elapsedTime = currentTime - startTime

        // 在这里处理你的计时逻辑
        print("Elapsed time: \(elapsedTime)")
    }
}