setupVisionAndDrawing.swift

 func setupVision() throws {
        guard let modelURL = Bundle.main.url(forResource: "yolov5n", withExtension: "mlmodelc") else {
            throw NSError(domain: "ViewController", code: -1, userInfo: [NSLocalizedDescriptionKey: "Model file is missing"])
        }
        
        do {
            let visionModel = try VNCoreMLModel(for: MLModel(contentsOf: modelURL))
            let objectRecognition = VNCoreMLRequest(model: visionModel, completionHandler: { (request, error) in
                DispatchQueue.main.async(execute: {
                    if let results = request.results {
                        self.drawResults(results)
                    }
                })
            })
            self.requests = [objectRecognition]
        } catch let error as NSError {
            print("Model loading went wrong: \(error)")
        }
    }

func drawResults(_ results: [Any]) {
        CATransaction.begin()
        CATransaction.setValue(kCFBooleanTrue, forKey: kCATransactionDisableActions)
        detectionLayer.sublayers = nil // Clear previous detections from detectionLayer
        inferenceTimeLayer.sublayers = nil
        for observation in results where observation is VNRecognizedObjectObservation {
            guard let objectObservation = observation as? VNRecognizedObjectObservation else {
                continue
            }
            
            let topLabelObservation = objectObservation.labels[0]
            
            let boundingBox = CGRect(origin: CGPoint(x:1.0-objectObservation.boundingBox.origin.y-objectObservation.boundingBox.size.height, y:objectObservation.boundingBox.origin.x), size: CGSize(width:objectObservation.boundingBox.size.height,height:objectObservation.boundingBox.size.width))
            
            let objectBounds = VNImageRectForNormalizedRect(boundingBox, Int(bufferSize.width), Int(bufferSize.height))
            
            let shapeLayer = createRectLayer(objectBounds, colors[topLabelObservation.identifier]!)
            
            let formattedString = NSMutableAttributedString(string: String(format: "\(topLabelObservation.identifier)\n %.1f%% ", topLabelObservation.confidence*100).capitalized)
            
            let textLayer = createDetectionTextLayer(objectBounds, formattedString)
            shapeLayer.addSublayer(textLayer)
            detectionLayer.addSublayer(shapeLayer)
        }
        
        let formattedInferenceTimeString = NSMutableAttributedString(string: String(format: "Inference time: %.1f ms ", inferenceTime*1000))
        
        let inferenceTimeTextLayer = createInferenceTimeTextLayer(inferenceTimeBounds, formattedInferenceTimeString)

        inferenceTimeLayer.addSublayer(inferenceTimeTextLayer)
        
        CATransaction.commit()
    }