ste7en / Share_Knowledge-VisionFaceDetection

Share Knowledge activity for Apple Developer Academy: Face Detection with Vision Framework

High performance image analysis with Vision Framework

Share Knowledge activity @Apple Developer Academy, Naples. This is a project example of Face Detection with Vision written Stefano Formicola and Gian Marco Orlando.

Try it out with real time face detection on your iPhone! 📱

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Guiding Activity

Use the Vision VNResult objects to draw on screen a face rectangle and facial landmarks. Use the swift file 'What to add.swift' to add the methods in the ViewController.swift.

Details

Specify the VNRequest for face recognition, either VNDetectFaceRectanglesRequest or VNDetectFaceLandmarksRequest.

private var requests = [VNRequest]() // you can do mutiple requests at the same time

var faceDetectionRequest: VNRequest!
@IBAction func UpdateDetectionType(_ sender: UISegmentedControl) {
    // use segmentedControl to switch over VNRequest
    faceDetectionRequest = sender.selectedSegmentIndex == 0 ? VNDetectFaceRectanglesRequest(completionHandler: handleFaces) : VNDetectFaceLandmarksRequest(completionHandler: handleFaceLandmarks) 
}

Perform the requests every single frame. The image comes from camera via captureOutput(_:didOutput:from:), see AVCaptureVideoDataOutputSampleBufferDelegate

Handle the return of your request, VNRequestCompletionHandler.

• handleFaces for VNDetectFaceRectanglesRequest
• handleFaceLandmarks for VNDetectFaceLandmarksRequest

then you will get the result from the request, which are VNFaceObservations. That's all you got from the Vision API

func handleFaces(request: VNRequest, error: Error?) {
    DispatchQueue.main.async {
        //perform all the UI updates on the main queue
        guard let results = request.results as? [VNFaceObservation] else { return }
        print("face count = \(results.count) ")
        self.previewView.removeMask()

        for face in results {
            self.previewView.drawFaceboundingBox(face: face)
        }
    }
}
    
func handleFaceLandmarks(request: VNRequest, error: Error?) {
    DispatchQueue.main.async {
        //perform all the UI updates on the main queue
        guard let results = request.results as? [VNFaceObservation] else { return }
        self.previewView.removeMask()
        for face in results {
            self.previewView.drawFaceWithLandmarks(face: face)
        }
    }
}