Swift - 人脸检测，以及人脸打码的功能实现（附样例）

import UIKit
import ImageIO

class ViewController: UIViewController {
    
    @IBOutlet weak var imageView: UIImageView!
    
    //原图
    lazy var originalImage: UIImage = {
        return UIImage(named: "d1.jpg")
        }()!
    
    lazy var context: CIContext = {
        return CIContext(options: nil)
        }()

    override func viewDidLoad() {
        super.viewDidLoad()
    }
    
    //恢复原图
    @IBAction func resetImg(sender: AnyObject) {
        imageView.image = originalImage
    }
    
    //检测人脸并框出
    @IBAction func detectFace(sender: AnyObject) {
        imageView.image = originalImage
        let inputImage = CIImage(image: originalImage)!
        //人脸检测器
        //CIDetectorAccuracyHigh:检测的精度高,但速度更慢些
        let detector = CIDetector(ofType: CIDetectorTypeFace,
            context: context,
            options: [CIDetectorAccuracy: CIDetectorAccuracyHigh])
        var faceFeatures: [CIFaceFeature]!
        //人脸检测需要图片方向(有元数据的话使用元数据,没有就调用featuresInImage)
        if let orientation: AnyObject = inputImage
            .properties[kCGImagePropertyOrientation as String] {
            faceFeatures = detector.featuresInImage(inputImage,
                options: [CIDetectorImageOrientation: orientation]) as! [CIFaceFeature]
        } else {
            faceFeatures = detector.featuresInImage(inputImage) as! [CIFaceFeature]
        }
        
        //打印所有的面部特征
        print(faceFeatures)
        
        let inputImageSize = inputImage.extent.size
        var transform = CGAffineTransformIdentity
        transform = CGAffineTransformScale(transform, 1, -1)
        transform = CGAffineTransformTranslate(transform, 0, -inputImageSize.height)
        
        //遍历所有的面部，并框出
        for faceFeature in faceFeatures {
            var faceViewBounds = CGRectApplyAffineTransform(faceFeature.bounds, transform)
            
            // 由于检测的原图放在imageView中缩放的原因,我们还要考虑缩放比例和x,y轴偏移
            let scale = min(imageView.bounds.size.width / inputImageSize.width,
                imageView.bounds.size.height / inputImageSize.height)
            let offsetX = (imageView.bounds.size.width - inputImageSize.width * scale) / 2
            let offsetY = (imageView.bounds.size.height - inputImageSize.height * scale) / 2
            
            faceViewBounds = CGRectApplyAffineTransform(faceViewBounds,
                CGAffineTransformMakeScale(scale, scale))
            faceViewBounds.origin.x += offsetX
            faceViewBounds.origin.y += offsetY
            
            //每个人脸对应一个UIView方框
            let faceView = UIView(frame: faceViewBounds)
            faceView.layer.borderColor = UIColor.orangeColor().CGColor
            faceView.layer.borderWidth = 2
            
            imageView.addSubview(faceView)
        }
    }
    
    //检测人脸并打马赛克
    @IBAction func detectAndPixFace(sender: AnyObject) {
        // 用CIPixellate滤镜对原图先做个完全马赛克
        let filter = CIFilter(name: "CIPixellate")!
        print(filter.attributes)
        let inputImage = CIImage(image: originalImage)!
        filter.setValue(inputImage, forKey: kCIInputImageKey)
        let inputScale = max(inputImage.extent.size.width, inputImage.extent.size.height) / 80
        filter.setValue(inputScale, forKey: kCIInputScaleKey)
        let fullPixellatedImage = filter.outputImage

        // 检测人脸，并保存在faceFeatures中
        let detector = CIDetector(ofType: CIDetectorTypeFace,
            context: context,
            options: nil)
        let faceFeatures = detector.featuresInImage(inputImage)
        // 初始化蒙版图，并开始遍历检测到的所有人脸
        var maskImage: CIImage!
        for faceFeature in faceFeatures {
            print(faceFeature.bounds)
            // 基于人脸的位置，为每一张脸都单独创建一个蒙版，所以要先计算出脸的中心点，对应为x、y轴坐标，
            // 再基于脸的宽度或高度给一个半径，最后用这些计算结果初始化一个CIRadialGradient滤镜
            let centerX = faceFeature.bounds.origin.x + faceFeature.bounds.size.width / 2
            let centerY = faceFeature.bounds.origin.y + faceFeature.bounds.size.height / 2
            let radius = min(faceFeature.bounds.size.width, faceFeature.bounds.size.height)
            let radialGradient = CIFilter(name: "CIRadialGradient",
                withInputParameters: [
                    "inputRadius0" : radius,
                    "inputRadius1" : radius + 1,
                    "inputColor0" : CIColor(red: 0, green: 1, blue: 0, alpha: 1),
                    "inputColor1" : CIColor(red: 0, green: 0, blue: 0, alpha: 0),
                    kCIInputCenterKey : CIVector(x: centerX, y: centerY)
                ])!
            print(radialGradient.attributes)
            // 由于CIRadialGradient滤镜创建的是一张无限大小的图，所以在使用之前先对它进行裁剪
            let radialGradientOutputImage = radialGradient.outputImage!
                .imageByCroppingToRect(inputImage.extent)
            if maskImage == nil {
                maskImage = radialGradientOutputImage
            } else {
                print(radialGradientOutputImage)
                maskImage = CIFilter(name: "CISourceOverCompositing",
                    withInputParameters: [
                        kCIInputImageKey : radialGradientOutputImage,
                        kCIInputBackgroundImageKey : maskImage
                    ])!.outputImage
            }
        }
        // 用CIBlendWithMask滤镜把马赛克图、原图、蒙版图混合起来
        let blendFilter = CIFilter(name: "CIBlendWithMask")!
        blendFilter.setValue(fullPixellatedImage, forKey: kCIInputImageKey)
        blendFilter.setValue(inputImage, forKey: kCIInputBackgroundImageKey)
        blendFilter.setValue(maskImage, forKey: kCIInputMaskImageKey)
        // 输出，在界面上显示
        let blendOutputImage = blendFilter.outputImage
        let blendCGImage = context.createCGImage(blendOutputImage!,
            fromRect: blendOutputImage!.extent)
        imageView.image = UIImage(CGImage: blendCGImage)

    }
    
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }
}