UISwitch BackgroundView Bug Demo Playground File

UISwitchBackgroundViewBugDemo.swift

import UIKit
import PlaygroundSupport

class MyViewController : UIViewController {
    override func loadView() {
        let view = UIStackView()
        view.alignment = .center
        view.distribution = .equalCentering
        view.axis = .horizontal
        view.backgroundColor = .black
        
        // UISwitch WITHOUT the cornerRadius set
        // NOTE: Color leaks out from UISwitch
        let redSwitch = UISwitch()
        redSwitch.backgroundColor = .red
        
        // UISwitch WITH the cornerRadius set
        let blueSwitch = UISwitch()
        blueSwitch.backgroundColor = .blue
        blueSwitch.layer.cornerRadius = 16
        
        view.addArrangedSubview(redSwitch)
        view.addArrangedSubview(blueSwitch)
        self.view = view
    }
}

PlaygroundPage.current.liveView = MyViewController()