connection: AVCaptureConnection ) { var handPoseRequest = VNDetectHumanHandPoseRequest() let handler = VNImageRequestHandler(cmSampleBuffer: sampleBuffer, …) try handler.perform([handPoseRequest]) let observation = handPoseRequest.results?.first as! VNRecognizedPointsObservation } AVCaptureVideoDataOutputSampleBufferDelegate AVCaptureSession AVCaptureVideoDataOutput