Output

Output.swift

// MARK: - Private functions

let handDetector = HandDetector()

private func startDetection() {
    // To avoid force unwrap in VNImageRequestHandler
    guard let buffer = currentBuffer else { return }

    handDetector.performDetection(inputBuffer: buffer) { outputBuffer, _ in
        // Here we are on a background thread
        var previewImage: UIImage?

        defer {
            DispatchQueue.main.async {
                self.previewView.image = previewImage
                // Release currentBuffer when finished to allow processing next frame
                self.currentBuffer = nil
            }
        }

        guard let outBuffer = outputBuffer else {
            return
        }

        // Create UIImage from CVPixelBuffer
        previewImage = UIImage(ciImage: CIImage(cvPixelBuffer: outBuffer))
    }
}