CGImageRef为零？

Question

我正在尝试使用AVFoundatin在我的应用中拍照。在didFinishProcessingPhoto块中，我运行一些代码来收集图像数据并创建要在预览屏幕中显示的图像。代码如下：

func photoOutput(_ output: AVCapturePhotoOutput, didFinishProcessingPhoto photo: AVCapturePhoto, error: Error?) {
    if let error = error {
        print("Error capturing photo: \(error)")
    } else {
        let photoData = photo.fileDataRepresentation()

        if let currentData = photoData {
            let dataProvider = CGDataProvider(data: currentData as CFData)
            let cgImageRef = CGImage(jpegDataProviderSource: dataProvider!, decode: nil, shouldInterpolate: true, intent: CGColorRenderingIntent.defaultIntent)
            let image = UIImage(cgImage: cgImageRef!, scale: 1.0, orientation: self.getImageOrientation(forCamera: self.videoDeviceInput.device.position))
            let containerView = PreviewPhotoContainerView()
            self.view.addSubview(containerView)
            containerView.previewImageView.image =  image
            containerView.snp.makeConstraints { (make) in
                make.edges.equalTo(self.view)
            }
        }
    }
}

但是，每次拍摄照片时，我都会得到一个错误，指出没有包装的东西为零。经过一番挖掘，我发现它是CGImageRef。但是，我看不到哪里出了问题。