我有一个自定义的UIPresentationController，其中我覆盖了presentedView，如下所示：

override var presentedView: UIView? {
        guard let view = super.presentedView else { return nil }
        
        let shadowLayer = CALayer()
        shadowLayer.shadowPath = .init(rect: view.bounds, transform: .none)
        shadowLayer.shadowRadius = 6
        shadowLayer.shadowColor = .init(gray: 0, alpha: 0.15)
        shadowLayer.backgroundColor = view.layer.backgroundColor
        shadowLayer.shadowOpacity = 1
        shadowLayer.shadowOffset = .init(width: 0, height: -10)
        shadowLayer.shouldRasterize = true
        shadowLayer.rasterizationScale = UIApplication.screen?.scale ?? 1.0
        
        view.layer.insertSublayer(shadowLayer, at: 0)
        shadowLayer.position = view.layer.position
        shadowLayer.bounds = view.bounds
        view.layer.masksToBounds = false
        
        return view
    }

然后为了效率，我想为什么每次计算presetedView时都要创建一个新的CALayer，并决定将层作为类的属性，只更新shadowPath。之后，该层不再可见，也不再位于视图层次结构中。我也尝试插入子层只有一次，通过检查层是否存在于子层，但它没有帮助
有人知道我错过了什么吗？

更新：申报房产

private let shadowLayer = {
        let shadowLayer = CALayer()
        shadowLayer.shadowRadius = 6
        shadowLayer.shadowOpacity = 1
        shadowLayer.shadowOffset = .init(width: 0, height: -10)
        shadowLayer.shouldRasterize = true
        shadowLayer.rasterizationScale = UIApplication.screen?.scale ?? 1.0
        shadowLayer.masksToBounds = false
        return shadowLayer
    }()

从这里删除了初始化代码。之后，图层消失

override var presentedView: UIView? {
        guard let view = super.presentedView else { return nil }
        

        shadowLayer.shadowPath = .init(rect: view.bounds, transform: .none)

        shadowLayer.shadowColor = .init(gray: 0, alpha: 0.15)
        shadowLayer.backgroundColor = view.layer.backgroundColor

        
        view.layer.insertSublayer(shadowLayer, at: 0)
        shadowLayer.position = view.layer.position
        shadowLayer.bounds = view.bounds
        view.layer.masksToBounds = false
        
        return view
    }