Vision Face Detector

vfd.swift

public class VisionFaceDetector {
    private var faceRectangleRequest: VNDetectFaceRectanglesRequest!
    
    public var boundingBoxes: [CGRect] = []
    
    public init() {
        self.faceRectangleRequest = VNDetectFaceRectanglesRequest(completionHandler: { [weak self] (request, error) in
            self?.handleFaces(request: request, error: error)
        })
        self.faceRectangleRequest.preferBackgroundProcessing = false
    }
    
    public func detectFaces(in image: UIImage) {
        let handler = VNImageRequestHandler(cgImage: image.cgImage!, options: [:])
        
        do { try handler.perform([self.faceRectangleRequest]) }
        catch { fatalError(error.localizedDescription) }
    }
    
    private func handleFaces(request: VNRequest, error: Error?) {
        guard error == nil else {
            fatalError(error!.localizedDescription)
        }
        
        guard let results = request.results as? [VNFaceObservation] else {
            fatalError()
        }
        
        guard results.count > 0 && results.count < 3 else {
            return
        }
        
        self.boundingBoxes = results.map { $0.boundingBox }
    }
}