如何在x-times中获取AVCaptureDevice videoZoomFactor？

Question

我已经实现了以下代码来获得正常工作的缩放因子

var maxZoomScale = CGFloat.greatestFiniteMagnitude
var beginZoomScale               = CGFloat(1.0)
var zoomScale                    = CGFloat(1.0)

fileprivate func zoomGesture(pinch: UIPinchGestureRecognizer) {
        guard pinchToZoom == true && self.currentCamera == .rear else {
            //ignore pinch
            return
        }
        do {
            let captureDevice = AVCaptureDevice.devices().first
            try captureDevice?.lockForConfiguration()

            zoomScale = min(maxZoomScale, max(1.0, min(beginZoomScale * pinch.scale,  captureDevice!.activeFormat.videoMaxZoomFactor)))

            captureDevice?.videoZoomFactor = zoomScale

            // Call Delegate function with current zoom scale
            DispatchQueue.main.async {
                print("zoomScale : \(self.zoomScale)")
                self.cameraDelegate?.swiftyCam(self, didChangeZoomLevel: self.zoomScale)
            }

            captureDevice?.unlockForConfiguration()

        } catch {
            print("Error locking configuration")
        }
    }

现在var zoomScale给了我最大缩放因子1.011的缩放因子，现在我已达到1.98。 我需要X-time ，如1x，2x，3x .... 那我该怎么办呢？