How to make simple search box in iOS

final class SearchBox: UIView {
    lazy var textField: UITextField = {
        let textField = UITextField()
        let imageView = UIImageView(image: R.image.search()!)
        imageView.frame.size = CGSize(width: 20 + 8, height: 20)
        imageView.contentMode = .scaleAspectFit
        textField.leftView = imageView
        textField.leftViewMode = .always

        return textField
    }()

    lazy var filterButton: UIButton = {
        let button = UIButton(type: .custom)
        button.setImage(R.image.filter()!, for: .normal)
        button.imageEdgeInsets = UIEdgeInsets(top: 10, left: 10, bottom: 10, right: 10)

        return button
    }()

    lazy var backView: UIView = {
        let view = UIView()
        view.backgroundColor = .white
        view.layer.cornerRadius = 10
        view.layer.borderColor = R.color.lightGray.cgColor
        view.layer.borderWidth = 0.5
        view.layer.shadowOffset = CGSize(width: 1, height: 1)
        view.layer.shadowOpacity = 0.8
        view.layer.shadowColor = R.color.lightGray.cgColor

        return view
    }()

    override init(frame: CGRect) {
        super.init(frame: frame)

        setup()
    }

    required init?(coder aDecoder: NSCoder) {
        fatalError()
    }

    private func setup() {
        addSubviews([backView, textField, filterButton])

        NSLayoutConstraint.on([
            filterButton.rightAnchor.constraint(equalTo: rightAnchor, constant: -8),
            filterButton.centerYAnchor.constraint(equalTo: centerYAnchor),
            filterButton.heightAnchor.constraint(equalToConstant: 44),
            filterButton.widthAnchor.constraint(equalToConstant: 44),

            textField.centerYAnchor.constraint(equalTo: centerYAnchor),
            textField.leftAnchor.constraint(equalTo: leftAnchor, constant: 16),
            textField.rightAnchor.constraint(equalTo: filterButton.leftAnchor, constant: -8)
        ])

        NSLayoutConstraint.on([
            backView.pinEdges(view: self, inset: UIEdgeInsets(top: 4, left: 4, bottom: -4, right: -4))
        ])
    }
}

imageView.frame.size = CGSize(width: 20 + 8, height: 20)
imageView.contentMode = .scaleAspectFit