I had a quick go at this a few months back using Apple's CIDetector[1], and even at 'high' accuracy that didn't seem precise enough — it was distractingly jiggl

I had a quick go at this a few months back using Apple's CIDetector[1], and even at 'high' accuracy that didn't seem precise enough — it was distractingly jiggly. [1] [CIDetector detectorOfType:CIDetectorTypeFace context:nil options:@{CIDetectorAccuracy: CIDetectorAccuracyHigh, CIDetectorTracking: @YES}]