Scroll text animation in Swift

MyViewController.swift

import UIKit
import PlaygroundSupport

class MyViewController : UIViewController {
    var label:UILabel!
    var label2:UILabel!
    let gap:CGFloat = 50
    let rep:Float = Float.infinity
    let shape:CAShapeLayer = {
        return CAShapeLayer()
    }()
    var state:Int = 0

    override func viewDidLoad() {
        self.view.backgroundColor = .white

        shape.frame = CGRect(x: 0, y: 0, width: 200, height: 50)
        shape.backgroundColor = UIColor.blue.cgColor
        shape.position = CGPoint(x:view.frame.width / 2, y:view.frame.height / 2)
        shape.masksToBounds = true

        label = trainingItemTitleLabel(width:200, color:.green)
        label.center = self.view.center
        label.text = "Hello"
        label.center = CGPoint(x:shape.frame.width / 2, y:shape.frame.height / 2)
        label2 = trainingItemTitleLabel(width:200, color:.red)
        label2.center = self.view.center
        label2.text = "Hello"
        label2.center = CGPoint(x:shape.frame.width / 2, y:shape.frame.height / 2 - gap)


        shape.addSublayer(label.layer)
        shape.addSublayer(label2.layer)
        let tmp = view.layer
        tmp.addSublayer(shape)
        view.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(handleTap)))

    }
    
    @objc func handleTap() {
        
        let animationPos = CABasicAnimation(keyPath: "position.y")
        animationPos.fromValue = label.layer.position.y
        animationPos.toValue = label.layer.position.y + gap
        animationPos.duration = 0.5
        animeKeep(anim:animationPos)

        let animationPos2 = CABasicAnimation(keyPath: "position.y")
        animationPos2.fromValue = label2.layer.position.y
        animationPos2.toValue = label2.layer.position.y + gap
        animationPos2.duration = 0.5
        animeKeep(anim:animationPos2)
        
        let mylayer = label.layer
        let mylayer2 = label2.layer
        if state == 0 {
            mylayer.add(animationPos, forKey: "animationPos")
            mylayer2.add(animationPos2, forKey: "animationPos2")
        } else {
            mylayer.add(animationPos2, forKey: "animationPos2")
            mylayer2.add(animationPos, forKey: "animationPos")
        }
        state = 1 - state
    }
    
    func animeKeep (anim:CABasicAnimation) {
        anim.fillMode = CAMediaTimingFillMode.forwards
        anim.isRemovedOnCompletion = false
    }

    func trainingItemTitleLabel(width:CGFloat, color: UIColor) -> UILabel {
        let label = UILabel()
        label.text = ""
        label.textAlignment = .center
        label.backgroundColor = .clear
        label.textColor = color
        label.font = UIFont.boldSystemFont(ofSize: 50)
        label.frame = CGRect(x: 0, y: 0, width: width, height: 50)
        // label.center = center
        return label
    }
}
// Present the view controller in the Live View window
PlaygroundPage.current.liveView = MyViewController()