AdjustableVisualEffectView.swift

class AdjustableVisualEffectView: UIVisualEffectView {

  private var animator: UIViewPropertyAnimator!

  init(effect: UIVisualEffect?, intensity: CGFloat) {
    super.init(effect: nil)
    self.animator = UIViewPropertyAnimator(duration: 1, curve: .linear) { [weak self] in
      self?.effect = effect
    }
    self.intensity = intensity
    animator.fractionComplete = intensity
  }

  var intensity: CGFloat = 0 {
    didSet {
      animator.fractionComplete = intensity
    }
  }

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

}