Adding UICollectionView with Custom Cell to UIViewController programmatically

UICollectionView+CustomCell+Programmatically.swift

//  Created by Evgeny Konkin on 17.06.2019.

class ViewController: UIViewController {
    
    var collectionView: UICollectionView!
    
    // MARK: - Views Life Cycles

    override func viewDidLoad() {
        super.viewDidLoad()
        setupCollectionView()
    }
    
    // MARK: - Setup Views
    
    func setupCollectionView() {
        let layout = UICollectionViewFlowLayout()
        layout.sectionInset = UIEdgeInsets(top: 0, left: 0, bottom: 0, right: 0)
        layout.itemSize = CGSize(width: view.frame.width, height: 300)
        
        collectionView = UICollectionView(frame: self.view.frame, collectionViewLayout: layout)
        collectionView.dataSource = self
        collectionView.delegate = self
        collectionView.backgroundColor = .white
        collectionView.showsVerticalScrollIndicator = false
        
        collectionView.register(CustomCell.self, forCellWithReuseIdentifier: CustomCell.identifier)        
        self.view.addSubview(collectionView)
    }
}

// MARK: - CollectionView DataSource Methods

extension WeatherViewController: UICollectionViewDataSource {
    
    func collectionView(_ collectionView: UICollectionView, numberOfItemsInSection section: Int) -> Int {
        return 10
    }
    
    func collectionView(_ collectionView: UICollectionView, cellForItemAt indexPath: IndexPath) -> UICollectionViewCell {
        let cell = collectionView.dequeueReusableCell(withReuseIdentifier: CustomCell.identifier, for: indexPath) as! CustomCell
        return cell
    }
    
}


// MARK: - Custom Cell Class
class CustomCell: UICollectionViewCell {
    
    static let identifier = "CustomCell"
    
    let label: UILabel = {
        let label = UILabel()
        label.text = "Custom Cell"
        label.textColor = .white
        label.backgroundColor = .blue
        label.translatesAutoresizingMaskIntoConstraints = false
        return label
    }()
    
    override init(frame: CGRect) {
        super.init(frame: frame)
        
        self.backgroundColor = .blue
        
        self.addSubview(label)
        label.centerXAnchor.constraint(equalTo: self.centerXAnchor).isActive = true
        label.leadingAnchor.constraint(equalTo: self.leadingAnchor, constant: 16).isActive = true
        label.trailingAnchor.constraint(equalTo: self.trailingAnchor, constant: 16).isActive = true
    }
    
    required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
    }
    
}

how to get onclick on label