Dimming controller

Dimming.swift

/// Dimming presenter
/// Code is mostly coming from apple doc: https://developer.apple.com/documentation/uikit/uipresentationcontroller
class DimmingPresentationController: UIPresentationController {
    private let backgroundColor: UIColor
    private lazy var dimmingView: UIView = {
        let view = UIView()

        view.backgroundColor = backgroundColor
        view.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(onTapped)))

        return view
    }()

    init(presentedViewController: UIViewController,
         presenting presentingViewController: UIViewController?,
         backgroundColor: UIColor) {
        self.backgroundColor = backgroundColor
        super.init(presentedViewController: presentedViewController, presenting: presentingViewController)
    }

    override open func presentationTransitionWillBegin() {
        let transitionCoordinator = presentingViewController.transitionCoordinator

        super.presentationTransitionWillBegin()

        guard let containerView = containerView else {
            return
        }

        dimmingView.frame = containerView.bounds
        dimmingView.alpha = 0

        containerView.addSubview(dimmingView)
        transitionCoordinator?.animate(alongsideTransition: { _ in self.dimmingView.alpha = 1 },
                                       completion: nil)
    }

    override open func presentationTransitionDidEnd(_ completed: Bool) {
        super.presentationTransitionDidEnd(completed)

        if !completed {
            dimmingView.removeFromSuperview()
        }
    }

    override open func dismissalTransitionWillBegin() {
        let transitionCoordinator = presentingViewController.transitionCoordinator

        super.dismissalTransitionWillBegin()
        transitionCoordinator?.animate(alongsideTransition: { _ in self.dimmingView.alpha = 0 },
                                       completion: nil)
    }

    override open func dismissalTransitionDidEnd(_ completed: Bool) {
        super.dismissalTransitionDidEnd(completed)

        if completed {
            dimmingView.removeFromSuperview()
        }
    }

    @objc
    private func onTapped() {
        presentingViewController.dismiss(animated: true, completion: nil)
    }
}