ios webrtc从本地发布者视图获取快照？

Question

我试图拍摄本地发布者视图的快照而未将发布者视图呈现为图像！

我搜索了很多示例，但对我无济于事，例如：Can't get screenshot of only the UIView which shows camera (AVCapturePhotoOutput) in Swift

Is it possible to take a snapshot of combined views including the camera?

我尝试了此代码，但无法正常工作，图片始终为零：

stillImageOutput.outputSettings = [AVVideoCodecKey:AVVideoCodecType.jpeg]
        if localView.captureSession.canAddOutput(stillImageOutput) {
            localView.captureSession.addOutput(stillImageOutput)
        }
        if let videoConnection = stillImageOutput.connection(with: AVMediaType.video) {
            stillImageOutput.captureStillImageAsynchronously(from: videoConnection) {
                (imageDataSampleBuffer, error) -> Void in
                guard let imageDataBuffer = imageDataSampleBuffer else { return }
                let imageData = UIImage.from(sampleBuffer: imageDataBuffer)
                print("captured")
            }
        }

有人可以解决吗？谢谢