Timer animation not starting

Question

I'm trying to animate a circular progress timer animation for a timer app, but the timer counts and the animation never starts.

import UIKit

class TimerPage: UIViewController {
    let timeLeftShapeLayer = CAShapeLayer()
    let bgShapeLayer = CAShapeLayer()
    var timeLeft: TimeInterval = 60
    var endTime: Date?
    var timeLabel =  UILabel()
    var timer = Timer()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        view.backgroundColor = UIColor(white: 0.94, alpha: 1.0)
        drawBgShape()
        drawTimeLeftShape()
        addTimeLabel()
        // here you define the fromValue, toValue and duration of your animation
        strokeIt.fromValue = 0
        strokeIt.toValue = 1
        strokeIt.duration = 60
        // add the animation to your timeLeftShapeLayer
        timeLeftShapeLayer.add(strokeIt, forKey: nil)
        // define the future end time by adding the timeLeft to now Date()
        endTime = Date().addingTimeInterval(timeLeft)
        timer = Timer.scheduledTimer(timeInterval: 0.1, target: self, selector: #selector(updateTime), userInfo: nil, repeats: true)
    }
    // here you create your basic animation object to animate the strokeEnd
    let strokeIt = CABasicAnimation(keyPath: "strokeEnd")
    
    func drawBgShape() {
        bgShapeLayer.path = UIBezierPath(arcCenter: CGPoint(x: view.frame.midX , y: view.frame.midY), radius:
            150, startAngle: (3*CGFloat.pi) / 2, endAngle: -CGFloat.pi / 2, clockwise: false).cgPath
        bgShapeLayer.strokeColor = UIColor.blue.cgColor
        bgShapeLayer.fillColor = UIColor.clear.cgColor
        bgShapeLayer.lineWidth = 15
        view.layer.addSublayer(bgShapeLayer)
    }
    func drawTimeLeftShape() {
        timeLeftShapeLayer.path = UIBezierPath(arcCenter: CGPoint(x: view.frame.midX , y: view.frame.midY), radius:
            100, startAngle: (3*CGFloat.pi) / 2, endAngle: -CGFloat.pi / 2, clockwise: false).cgPath
        timeLeftShapeLayer.strokeColor = UIColor.white.cgColor
        timeLeftShapeLayer.fillColor = UIColor.clear.cgColor
        timeLeftShapeLayer.lineWidth = 15
        view.layer.addSublayer(timeLeftShapeLayer)
    }
    func addTimeLabel() {
        timeLabel = UILabel(frame: CGRect(x: view.frame.midX-50 ,y: view.frame.midY-25, width: 100, height: 50))
        timeLabel.textAlignment = .center
        timeLabel.text = timeLeft.time
        view.addSubview(timeLabel)
    }
    @objc func updateTime() {
    if timeLeft > 0 {
        timeLeft = endTime?.timeIntervalSinceNow ?? 0
        timeLabel.text = timeLeft.time
        } else {
        timeLabel.text = "00:00"
        timer.invalidate()
        }
    }
}
extension TimeInterval {
    var time: String {
        return String(format:"%02d:%02d", Int(self/60),  Int(ceil(truncatingRemainder(dividingBy: 60))) )
    }
}

I tested this out on a separate test project by itself, and it works perfectly fine. But when I add it to my actual app as part of a segue, the animation never starts.