Reshape Face Coordinate in Swift - swift

Question

I want to reshape the face coordinate like showing in the video: https://www.dropbox.com/s/vsttylwgt25szha/IMG_6590.TRIM.MOV?dl=0 (Sorry, unfortunetly the video is about 11 MB in size).
I've just capture the face coordinate using iOS Vision API:
// Facial landmarks are GREEN.
fileprivate func drawFeatures(onFaces faces: [VNFaceObservation], onImageWithBounds bounds: CGRect) {
CATransaction.begin()
for faceObservation in faces {
let faceBounds = boundingBox(forRegionOfInterest: faceObservation.boundingBox, withinImageBounds: bounds)
guard let landmarks = faceObservation.landmarks else {
continue
}
// Iterate through landmarks detected on the current face.
let landmarkLayer = CAShapeLayer()
let landmarkPath = CGMutablePath()
let affineTransform = CGAffineTransform(scaleX: faceBounds.size.width, y: faceBounds.size.height)
// Treat eyebrows and lines as open-ended regions when drawing paths.
let openLandmarkRegions: [VNFaceLandmarkRegion2D?] = [
//landmarks.leftEyebrow,
//landmarks.rightEyebrow,
landmarks.faceContour,
landmarks.noseCrest,
// landmarks.medianLine
]
// Draw eyes, lips, and nose as closed regions.
let closedLandmarkRegions = [
landmarks.nose
].compactMap { $0 } // Filter out missing regions.
// Draw paths for the open regions.
for openLandmarkRegion in openLandmarkRegions where openLandmarkRegion != nil {
landmarkPath.addPoints(in: openLandmarkRegion!,
applying: affineTransform,
closingWhenComplete: false)
}
// Draw paths for the closed regions.
for closedLandmarkRegion in closedLandmarkRegions {
landmarkPath.addPoints(in: closedLandmarkRegion ,
applying: affineTransform,
closingWhenComplete: true)
}
// Format the path's appearance: color, thickness, shadow.
landmarkLayer.path = landmarkPath
landmarkLayer.lineWidth = 1
landmarkLayer.strokeColor = UIColor.green.cgColor
landmarkLayer.fillColor = nil
landmarkLayer.shadowOpacity = 1.0
landmarkLayer.shadowRadius = 1
// Locate the path in the parent coordinate system.
landmarkLayer.anchorPoint = .zero
landmarkLayer.frame = faceBounds
landmarkLayer.transform = CATransform3DMakeScale(1, -1, 1)
pathLayer?.addSublayer(landmarkLayer)
}
CATransaction.commit()
}
How to step forward from here? Can anyone guide me please?