RoundedViewPlusShadow

RoundedViewPlusShadow.playground

import UIKit
import PlaygroundSupport

let subviewFrame = CGRect(x: 50, y: 50, width: 300, height: 300)
let subview = UIView(frame: subviewFrame)
subview.backgroundColor = .yellow

subview.layer.cornerRadius = 20

subview.layer.shadowColor = UIColor.black.cgColor
subview.layer.shadowOffset = CGSize(width: 0, height: 3)
subview.layer.shadowOpacity = 0.3
subview.layer.shadowRadius = 4

let containerViewFrame = CGRect(x: 0, y: 0, width: 400, height: 400)
let containerView = UIView(frame: containerViewFrame)
containerView.backgroundColor = .white
containerView.addSubview(subview)

PlaygroundPage.current.liveView = containerView