如何在运行时改变网格视图行的颜色？

import UIKit

class ViewController: UIViewController, UICollectionViewDataSource, UICollectionViewDelegate {
    @IBOutlet weak var collectionView: UICollectionView!
    
    var colors = [UIColor.red, UIColor.blue, UIColor.green, UIColor.yellow]
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        collectionView.dataSource = self
        collectionView.delegate = self
    }
    
    // 设置网格视图的行数
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return colors.count
    }
    
    // 设置网格视图的单元格
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "Cell", for: indexPath)
        
        // 根据行数设置单元格的背景颜色
        cell.backgroundColor = colors[indexPath.row]
        
        return cell
    }
    
    // 点击单元格时改变颜色
    func collectionView(_ collectionView: UICollectionView, didSelectItemAt indexPath: IndexPath) {
        // 随机生成一个新的颜色
        let newColor = UIColor.random()
        
        // 替换原来的颜色
        colors[indexPath.row] = newColor
        
        // 刷新网格视图
        collectionView.reloadData()
    }
}

// 生成随机颜色的扩展
extension UIColor {
    static func random() -> UIColor {
        let red = CGFloat.random(in: 0...1)
        let green = CGFloat.random(in: 0...1)
        let blue = CGFloat.random(in: 0...1)
        
        return UIColor(red: red, green: green, blue: blue, alpha: 1.0)
    }
}