Face detection in iOS with CIFaceFeature

Question

For a professional project, I need to detect a person from his picture. So I can get CIFaceFeature for each face.

Then I would get unique values ​​for each face to the identifiers.

I looked on the side of TrackingID, but this one is always equal to 0. I also made ​​some calculations with the position of the eyes and mouth but it depant the distance of the face compared to the iPhone.

   -(void)detectForFacesInUIImage:(UIImage *)facePicture
  {
    CIImage* image = [CIImage imageWithCGImage:facePicture.CGImage];

   //    CIDetector* detector = [CIDetector detectorOfType:CIDetectorTypeFace
   //  context:nil options:[NSDictionary dictionaryWithObject:CIDetectorAccuracyLow forKey:CIDetectorAccuracy]];

       NSArray* features = [detector featuresInImage:image];

  for(CIFaceFeature* faceObject in features)
 {
    CGRect modifiedFaceBounds = faceObject.bounds;
    modifiedFaceBounds.origin.y = facePicture.size.height-faceObject.bounds.size.height-faceObject.bounds.origin.y;

    CGPoint c = [faceObject leftEyePosition];
    NSLog(@"left eye position %f %f = %f", c.x, c.y, c.y - c.x);

    c = [faceObject rightEyePosition];
    NSLog(@"right eye position %f %f = %f", c.x, c.y, c.y - c.x);

    c = [faceObject mouthPosition];
    NSLog(@"mouth eye position %f %f = %f", c.x, c.y, c.y - c.x);

    CGRect d = [faceObject bounds];
    NSLog(@"bounds eye position %f %f", d.size.width, d.size.height);

    NSLog(@"trackID = %d", faceObject.trackingID);
    NSLog(@"\n\n");
    [self addSubViewWithFrame:modifiedFaceBounds];

    if(faceObject.hasLeftEyePosition)
    {

        CGRect leftEye = CGRectMake(faceObject.leftEyePosition.x,(facePicture.size.height-faceObject.leftEyePosition.y), 10, 10);
        [self addSubViewWithFrame:leftEye];
    }

    if(faceObject.hasRightEyePosition)
    {

        CGRect rightEye = CGRectMake(faceObject.rightEyePosition.x, (facePicture.size.height-faceObject.rightEyePosition.y), 10, 10);
        [self addSubViewWithFrame:rightEye];

    }
    if(faceObject.hasMouthPosition)
    {
        CGRect  mouth = CGRectMake(faceObject.mouthPosition.x,facePicture.size.height-faceObject.mouthPosition.y,10, 10);
        [self addSubViewWithFrame:mouth];

        }
      }
    }