Category for calculating the rotation of a face detected with CoreImage face detection.
The category adds a method to CIFaceFeature called faceRotation which returns the angle of the face in radians.
The angle of the face is positive if tilted left and negative if tilted right. 0° would represent a perfectly up and down face.
CIFaceFeature+FaceRotation is available under the MIT license. See the LICENSE file for more info.