Draw face rectangle on UIView by converting and transforming from UIGraphics coordinate to UIView coordinates with sample buffer in Swift 4.2

DrawFaceRect.swift

private func drawFaceRectangle(sampleBuffer: CMSampleBuffer, detectedFaceRect: CGRect) {
        
        let pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer)
        let cameraImage = CIImage(cvPixelBuffer: pixelBuffer!)
        
        
        // For converting the Core Image Coordinates to UIView Coordinates
        let ciImageSize = cameraImage.extent.size
        var transform = CGAffineTransform(scaleX: 1, y: -1)
        transform = transform.translatedBy(x: 0, y: -ciImageSize.height)
        
        // Apply the transform to convert the coordinates
        var faceViewBounds = detectedFaceRect.applying(transform)
        
        // Calculate the actual position and size of the rectangle in the image view
        let viewSize = self.layer.bounds.size
        let scale = min(viewSize.width / ciImageSize.width,
                        viewSize.height / ciImageSize.height)
        let offsetX = (viewSize.width - ciImageSize.width * scale) / 2
        let offsetY = (viewSize.height - ciImageSize.height * scale) / 2
        
        faceViewBounds = faceViewBounds.applying(CGAffineTransform(scaleX: scale, y: scale))
        faceViewBounds.origin.x += offsetX
        faceViewBounds.origin.y += offsetY
        
        let faceRect = faceViewBounds.insetBy(dx: -40, dy: -40)
        
        DispatchQueue.main.async {
            
            if self.shapeLayer == nil {
                
                self.shapeLayer = CAShapeLayer()
                self.shapeLayer.name = "CornersLayer"
                self.shapeLayer.strokeColor = UIColor.white.cgColor
                self.shapeLayer.fillColor = UIColor.clear.cgColor
                self.shapeLayer.lineWidth = 7.0
                self.shapeLayer.lineCap = .round
                self.shapeLayer.lineJoin = .round
                self.shapeLayer.frame = self.layer.bounds
                
                self.layer.addSublayer(self.shapeLayer)
            }
            
            let cornerLengthToShow = self.layer.bounds.size.height * 0.04
            
            // Create Paths Using BeizerPath for all four corners
            let topLeftCorner = UIBezierPath()
            topLeftCorner.move(to: CGPoint(x: faceRect.minX, y: faceRect.minY + cornerLengthToShow))
            topLeftCorner.addLine(to: CGPoint(x: faceRect.minX, y: faceRect.minY))
            topLeftCorner.addLine(to: CGPoint(x: faceRect.minX + cornerLengthToShow, y: faceRect.minY))
            
            let topRightCorner = UIBezierPath()
            topRightCorner.move(to: CGPoint(x: faceRect.maxX - cornerLengthToShow, y: faceRect.minY))
            topRightCorner.addLine(to: CGPoint(x: faceRect.maxX, y: faceRect.minY))
            topRightCorner.addLine(to: CGPoint(x: faceRect.maxX, y: faceRect.minY + cornerLengthToShow))
            
            let bottomRightCorner = UIBezierPath()
            bottomRightCorner.move(to: CGPoint(x: faceRect.maxX, y: faceRect.maxY - cornerLengthToShow))
            bottomRightCorner.addLine(to: CGPoint(x: faceRect.maxX, y: faceRect.maxY))
            bottomRightCorner.addLine(to: CGPoint(x: faceRect.maxX - cornerLengthToShow, y: faceRect.maxY ))
            
            let bottomLeftCorner = UIBezierPath()
            bottomLeftCorner.move(to: CGPoint(x: faceRect.minX, y: faceRect.maxY - cornerLengthToShow))
            bottomLeftCorner.addLine(to: CGPoint(x: faceRect.minX, y: faceRect.maxY))
            bottomLeftCorner.addLine(to: CGPoint(x: faceRect.minX + cornerLengthToShow, y: faceRect.maxY))
            
            let combinedPath = CGMutablePath()
            combinedPath.addPath(topLeftCorner.cgPath)
            combinedPath.addPath(topRightCorner.cgPath)
            combinedPath.addPath(bottomRightCorner.cgPath)
            combinedPath.addPath(bottomLeftCorner.cgPath)
            
            self.shapeLayer.path = combinedPath
        }
    }

Hey @fukemy
This func copied from my project that’s why I forgot to edit missing components.
Simply you can define CAShapelayer to avoid these errors.
Happy Coding