setupLayers.swift

func setupLayers() {
        previewLayer = AVCaptureVideoPreviewLayer(session: session)
        previewLayer.videoGravity = AVLayerVideoGravity.resizeAspectFill
        rootLayer = previewView.layer
        previewLayer.frame = rootLayer.bounds
        rootLayer.addSublayer(previewLayer)
        
        inferenceTimeBounds = CGRect(x: rootLayer.frame.midX-75, y: rootLayer.frame.maxY-70, width: 150, height: 17)
        
        inferenceTimeLayer = createRectLayer(inferenceTimeBounds, [1,1,1,1])
        inferenceTimeLayer.cornerRadius = 7
        rootLayer.addSublayer(inferenceTimeLayer)
        
        detectionLayer = CALayer()
        detectionLayer.bounds = CGRect(x: 0.0,
                                         y: 0.0,
                                         width: bufferSize.width,
                                         height: bufferSize.height)
        detectionLayer.position = CGPoint(x: rootLayer.bounds.midX, y: rootLayer.bounds.midY)
        rootLayer.addSublayer(detectionLayer)
        
        let xScale: CGFloat = rootLayer.bounds.size.width / bufferSize.height
        let yScale: CGFloat = rootLayer.bounds.size.height / bufferSize.width
        
        let scale = fmax(xScale, yScale)
    
        detectionLayer.setAffineTransform(CGAffineTransform(rotationAngle: CGFloat(.pi / 2.0)).scaledBy(x: scale, y: -scale))
        detectionLayer.position = CGPoint(x: rootLayer.bounds.midX, y: rootLayer.bounds.midY)
    }