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CIDetectorTypeFace: How to detect faces in a UIImage

Paul Hudson       @twostraws

Core Image has a number of feature detectors built right in, including the ability to detect faces, eyes, mouths, smiles and even blinking in pictures. When you ask it to look for faces in a picture, it will return you an array of all the faces it found, with each one containing face feature details such as eye position. Here's an example:

if let inputImage = UIImage(named: "taylor-swift") {
    let ciImage = CIImage(cgImage: inputImage.cgImage!)

    let options = [CIDetectorAccuracy: CIDetectorAccuracyHigh]
    let faceDetector = CIDetector(ofType: CIDetectorTypeFace, context: nil, options: options)!

    let faces = faceDetector.features(in: ciImage)

    if let face = faces.first as? CIFaceFeature {
        print("Found face at \(face.bounds)")

        if face.hasLeftEyePosition {
            print("Found left eye at \(face.leftEyePosition)")
        }

        if face.hasRightEyePosition {
            print("Found right eye at \(face.rightEyePosition)")
        }

        if face.hasMouthPosition {
            print("Found mouth at \(face.mouthPosition)")
        }
    }
}

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