         var comfortVelocity = velocity
         comfortVelocity.x *= 2.0
         
-        let options: UIViewAnimationOptions
+        let options: UIView.AnimationOptions
         if abs(comfortVelocity.x) > 0 {
             options = .curveEaseOut
             duration = durationForDistance(distance: maxDistance, velocity: abs(comfortVelocity.x))
         }
         else {
-            options = UIViewAnimationOptions()
+            options = UIView.AnimationOptions()
             duration = defaultCancelPopDuration
         }
         

    
    // MARK: UINavigationControllerDelegate
    
    public func navigationController(_ navigationController: UINavigationController, animationControllerFor operation: UINavigationControllerOperation, from fromVC: UIViewController, to toVC: UIViewController) -> UIViewControllerAnimatedTransitioning? {
        if (isInteractivelyPopping && operation == .pop) {
            return interactivePopAnimator
        }

        let maxToViewOffset = maxDistance * maxBackViewTranslationPercentage
        let resolvedToViewOffset = -maxToViewOffset
        let duration: TimeInterval
        let options: UIView.AnimationOptions
        
        if abs(velocity.x) > minimumThresholdVelocity {
            options = .curveEaseOut
