如何在swift中使用多节骨架加载？

import UIKit

class SkeletonViewController: UIViewController {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        let containerView = UIView(frame: CGRect(x: 0, y: 0, width: 200, height: 200))
        containerView.center = view.center
        view.addSubview(containerView)
        
        let skeletonView1 = UIView(frame: CGRect(x: 0, y: 0, width: 100, height: 20))
        skeletonView1.backgroundColor = .lightGray
        skeletonView1.layer.cornerRadius = 10
        containerView.addSubview(skeletonView1)
        
        let skeletonView2 = UIView(frame: CGRect(x: 0, y: 30, width: 150, height: 20))
        skeletonView2.backgroundColor = .lightGray
        skeletonView2.layer.cornerRadius = 10
        containerView.addSubview(skeletonView2)
        
        UIView.animate(withDuration: 1.0, delay: 0.0, options: [.repeat, .autoreverse], animations: {
            skeletonView1.alpha = 0.5
            skeletonView2.alpha = 0.5
        }, completion: nil)
    }
}