在UICollectionViewCell中更新渐变

class CustomCollectionViewCell: UICollectionViewCell {
    private var gradientLayer: CAGradientLayer?
    
    override func layoutSubviews() {
        super.layoutSubviews()
        
        if gradientLayer == nil {
            gradientLayer = CAGradientLayer()
            gradientLayer?.frame = bounds
            gradientLayer?.colors = [UIColor.red.cgColor, UIColor.blue.cgColor]
            gradientLayer?.startPoint = CGPoint(x: 0, y: 0)
            gradientLayer?.endPoint = CGPoint(x: 1, y: 1)
            
            layer.insertSublayer(gradientLayer!, at: 0)
        }
    }
}

func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: "CustomCell", for: indexPath) as! CustomCollectionViewCell
    
    // 更新渐变效果
    cell.gradientLayer?.colors = [UIColor.yellow.cgColor, UIColor.orange.cgColor]
    
    return cell
}