Transparent background for modally presented viewcontroller

same as the selected answer but visually through IB:

Part of the solution is hidden in the question. You need three lines to make the background transparent, viz. isOpaque = false backgroundColor = .clear & set the modalPresentationStyle

Here's the full solution. In the calling View Controller, call this function:

func presentModal() {
    let modalController = ModalViewController()
    modalViewController.modalPresentationStyle = .overCurrentContext
    present(modalViewController, animated: true, completion: nil)
}

And in ModalViewController's viewDidLoad():

override func viewDidLoad() {
    super.viewDidLoad()

    view.isOpaque = false
    view.backgroundColor = .clear // try other colors, say: .white or black with Alpha etc.
}

Fixed it.

The problem was that presentViewController does not keep the view that I was covering.

viewController.modalPresentationStyle = .overCurrentContext

did the trick.