iOS cards with cornerRadius and shadow in UICollectionView [Swift 4 Playground]

playground.swift

//: A UIKit based Playground for presenting user interface

import UIKit
import PlaygroundSupport

class CardView: UICollectionViewCell {
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        setupView()
    }
    
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }
    
    func setupView() {
        backgroundColor = UIColor.white
        
        let backgroundView = UIView()
        backgroundView.backgroundColor = UIColor.red
        backgroundView.layer.shadowRadius = 16
        backgroundView.layer.shadowColor = UIColor.black.cgColor
        backgroundView.layer.shadowOpacity = 1
        backgroundView.layer.shadowOffset = CGSize(width: 0, height: 0)
        backgroundView.translatesAutoresizingMaskIntoConstraints = false
        addSubview(backgroundView)
        
        let mainView = UIView()
        mainView.backgroundColor = UIColor.lightGray
        mainView.translatesAutoresizingMaskIntoConstraints = false
        mainView.layer.cornerRadius = 16
        addSubview(mainView)
        
        var constraints = [NSLayoutConstraint]()
        
        constraints += NSLayoutConstraint.constraints(withVisualFormat: "V:|-32-[backgroundView]-32-|", metrics: nil, views: ["backgroundView": backgroundView])
        constraints += NSLayoutConstraint.constraints(withVisualFormat: "H:|-32-[backgroundView]-32-|", metrics: nil, views: ["backgroundView": backgroundView])
        
        constraints += NSLayoutConstraint.constraints(withVisualFormat: "V:|-27-[mainView]-27-|", metrics: nil, views: ["mainView": mainView])
        constraints += NSLayoutConstraint.constraints(withVisualFormat: "H:|-27-[mainView]-27-|", metrics: nil, views: ["mainView": mainView])
        
        NSLayoutConstraint.activate(constraints)
    }
    
}

class CardsCollectionViewController : UICollectionViewController {
    
    override func viewDidLoad() {
        super.viewDidLoad()
        setupView()
    }
    
    func setupView() {
        collectionView?.register(CardView.self, forCellWithReuseIdentifier: "CardView")
        collectionView?.backgroundColor = UIColor.white
    }
    
    override func numberOfSections(in collectionView: UICollectionView) -> Int {
        return 1
    }
    
    override func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return 10
    }
    
    override func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cardView = collectionView.dequeueReusableCell(withReuseIdentifier: "CardView", for: indexPath)
        return cardView
    }
    
}

extension CardsCollectionViewController: UICollectionViewDelegateFlowLayout  {

    func collectionView(_ collectionView: UICollectionView, layout collectionViewLayout: UICollectionViewLayout, sizeForItemAt indexPath: IndexPath) -> CGSize {
        return CGSize(width: collectionView.frame.width, height: 300)
    }

}

// Present the view controller in the Live View window
PlaygroundPage.current.liveView = CardsCollectionViewController(collectionViewLayout: UICollectionViewFlowLayout())
PlaygroundPage.current.needsIndefiniteExecution = true