我如何强迫"容器"UIView没有CALayer？

class CustomView: UIView {
    override class var layerClass: AnyClass {
        return CustomLayer.self
    }
}

class CustomLayer: CALayer {
    override init() {
        super.init()
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
}

class CustomView: UIView {
    override init(frame: CGRect) {
        super.init(frame: frame)
        layer = nil
    }
    
    required init?(coder: NSCoder) {
        super.init(coder: coder)
        layer = nil
    }
}

UIGraphicsBeginImageContext(size)
let context = UIGraphicsGetCurrentContext()
// 绘制图形
let image = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()