Horizontal CollectionView with paging and center content inset (with shadow) (Variant 2: Cell with subview)

Sample.swift

import UIKit

class CollectionCell: UICollectionViewCell {
    
    static let reuseIdentifier = "CollectionCell"
    
    var card: UIView!
    var label: UILabel!
    var isInstalled = false
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        
        card = UIView(frame: .zero)
        addSubview(card)
        card.snp.makeConstraints { (make) in
            make.edges.equalToSuperview().inset(20)
        }
        
        label = UILabel(frame: .zero)
        label.textAlignment = .center
        card.addSubview(label)
        label.snp.makeConstraints { (make) in
            make.edges.equalToSuperview()
        }
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
    func setup(text: String) {
        label.text = text
    }
    
    override func layoutSubviews() {
        super.layoutSubviews()
        
        if isInstalled {
            return
        }
        
        isInstalled = true
        
        card.dropShadow(roundedRect: card.bounds,
                        cornerRadius: 30,
                        fillColor: UIColor.white,
                        shadowColor: UIColor.black,
                        shadowOffset: CGSize(width: 0, height: 8),
                        shadowOpacity: 0.1,
                        shadowRadius: 15)
    }
}

class CollectionViewController: UIViewController {
    
    var collectionView: UICollectionView!
    
    override var preferredStatusBarStyle: UIStatusBarStyle {
        return .default
    }
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        view.backgroundColor = UIColor.white
        
        let layout = UICollectionViewFlowLayout()
        layout.scrollDirection = .horizontal
        layout.minimumLineSpacing = 0
        layout.minimumInteritemSpacing = 0
        
        collectionView = UICollectionView(frame: .zero, collectionViewLayout: layout)
        collectionView.register(CollectionCell.self, forCellWithReuseIdentifier: CollectionCell.reuseIdentifier)
        collectionView.isPagingEnabled = true
        collectionView.delegate = self
        collectionView.dataSource = self
        collectionView.layer.masksToBounds = false
        collectionView.showsHorizontalScrollIndicator = false
        view.addSubview(collectionView)
        
        collectionView.backgroundColor = UIColor.clear
        collectionView.snp.makeConstraints { (make) in
            make.center.equalToSuperview()
            make.leading.trailing.equalToSuperview()
            make.height.equalTo(350)
        }
    }
}

extension CollectionViewController: UICollectionViewDataSource  {
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return 5
    }
    
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: CollectionCell.reuseIdentifier, for: indexPath) as! CollectionCell
        cell.setup(text: "\(indexPath.section) -> \(indexPath.row)")
        return cell
    }
}

extension CollectionViewController: UICollectionViewDelegateFlowLayout {
    func collectionView(_ collectionView: UICollectionView,
                        layout collectionViewLayout: UICollectionViewLayout,
                        sizeForItemAt indexPath: IndexPath) -> CGSize {
        let bounds = collectionView.bounds.size
        return CGSize(width: bounds.width, height: bounds.height)
    }
}