如何为CNContactPickerViewcontroller的背景添加模糊效果？

Question

我想更改CNContactPickerViewcontroller实例的背景，以使其具有与黑暗模式下的iOS13上的警报视图控制器类似的模糊效果。

controller.view.backgroundColor = .clear
controller.view.isOpaque = false

let blurEffect = UIBlurEffect(style: .dark)
let blurEffectView = UIVisualEffectView(effect: blurEffect)
blurEffectView.frame = controller.view.bounds
blurEffectView.autoresizingMask = [.flexibleWidth, .flexibleHeight]

visualEffectView = blurEffectView
controller.view.addSubview(blurEffectView)

它似乎不起作用。

我也尝试了没有运气的子类化：

class ContactViewController: CNContactViewController {
    override func viewDidLoad() {
        if !UIAccessibility.isReduceTransparencyEnabled {
            let blurEffect = UIBlurEffect(style: .light)
            let blurEffectView = UIVisualEffectView(effect: blurEffect)
            blurEffectView.frame = view.bounds
            blurEffectView.autoresizingMask = [.flexibleWidth, .flexibleHeight]
            view.backgroundColor = .clear
            view.addSubview(blurEffectView)
        }
    }
}