如何让CGContextDrawPath在嵌套子视图上绘制？

import UIKit

class CustomView: UIView {
    override func draw(_ rect: CGRect) {
        guard let context = UIGraphicsGetCurrentContext() else { return }
        
        // 在这里使用CGContextDrawPath绘制图形
        context.move(to: CGPoint(x: 50, y: 50))
        context.addLine(to: CGPoint(x: 150, y: 150))
        context.setStrokeColor(UIColor.red.cgColor)
        context.setLineWidth(2)
        context.strokePath()
    }
}

class ParentView: UIView {
    private var customView: CustomView!
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        setupSubviews()
    }
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        setupSubviews()
    }
    
    private func setupSubviews() {
        customView = CustomView()
        addSubview(customView)
    }
    
    override func layoutSubviews() {
        super.layoutSubviews()
        customView.frame = bounds
        customView.setNeedsDisplay()
    }
}