A view that combines shadow, corner radius, and translucent background into one view

ShadowCutoutView.swift

class ShadowCutoutView: UIView {
    var contentView: UIView? {
        didSet {
            oldValue?.removeFromSuperview()

            guard let contentView else {
                return
            }

            contentView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
            addSubview(contentView)
        }
    }

    let shadowLayer = CALayer()

    private let shadowMaskLayer = CAShapeLayer()

    override init(frame: CGRect) {
        super.init(frame: frame)

        shadowLayer.mask = shadowMaskLayer
        layer.addSublayer(shadowLayer)
    }
    
    required init?(coder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }

    override func layoutSubviews() {
        super.layoutSubviews()

        let shadowCornerRadius = contentView?.layer.cornerRadius ?? 0
        let shadowPadding = shadowLayer.shadowRadius * 4

        shadowLayer.frame = bounds
        shadowLayer.shadowPath = UIBezierPath(roundedRect: bounds, cornerRadius: shadowCornerRadius).cgPath

        let maskFrame = CGRect(
            x: -shadowPadding,
            y: -shadowPadding,
            width: bounds.width + shadowPadding * 2,
            height: bounds.height + shadowPadding * 2
        )
        let maskPath = UIBezierPath(rect: CGRect(origin: .zero, size: maskFrame.size))
        let cutoutPath = UIBezierPath(
            roundedRect: bounds.offsetBy(dx: shadowPadding, dy: shadowPadding),
            cornerRadius: shadowCornerRadius
        )
        maskPath.append(cutoutPath.reversing())

        shadowMaskLayer.frame = maskFrame
        shadowMaskLayer.path = maskPath.cgPath
    }
}

// Shadow parameters are adjusted through `shadowLayer` property instead
let view = ShadowCutoutView()
view.shadowLayer.shadowOffset = .zero
view.shadowLayer.shadowColor = UIColor.black.cgColor
view.shadowLayer.shadowRadius = 20
view.shadowLayer.shadowOpacity = 1

// Shadow corner radius is determined by corner radius of the content view
let contentView = UIView()
contentView.clipsToBounds = true
contentView.layer.cornerRadius = 20
view.contentView = contentView

This view allows you to have shadow, corner radius, and a translucent background all at the same time. You can adjust shadow parameters by changing corresponding properties on shadowLayer instead of regular layer property.
Shadow automatically adjusts its corner radius based on corner radius of its content view.

Translucent UIView	UIVisualEffectView