iOS 人脸识别(检测)

本文用的是系统自带的人脸识别功能，跟扫二维码条形码是一样的，但是系统只能识别出这是人的脸，至于高级的判断这张脸是谁的，需要更高级的第三方库了。

这里是检测到有人脸，然后三秒后自动拍照并存储到本地。

import UIKit
import ImageIO
import AVFoundation

class ScanFaceViewController: UIViewController, AVCaptureMetadataOutputObjectsDelegate {
    
    fileprivate var session = AVCaptureSession()
    fileprivate var stillImageOutput = AVCaptureStillImageOutput()
    fileprivate var layer = AVCaptureVideoPreviewLayer()
    fileprivate var timer: Timer?
    fileprivate var label = UILabel()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        self.label.frame = CGRect(x: 0, y: 100, width: ScreenWidth, height: 21)
        self.label.text = "等待验证"
        self.label.textColor = UIColor.red
        self.navigationController?.view.addSubview(self.label)
        
        self.startSession()
    }
    
    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)
        self.label.removeFromSuperview()
    }
    
    fileprivate func startSession() {
        var captureDevice: AVCaptureDevice?
        if let array = AVCaptureDevice.devices() {
            for i in array {
                let device = i as! AVCaptureDevice
                if device.hasMediaType(AVMediaTypeVideo) {
                    if device.position == AVCaptureDevicePosition.front {
                        captureDevice = device
                        break
                    }
                }
            }
        }else {
            return
        }
        do {
            let input = try AVCaptureDeviceInput.init(device: captureDevice)
            let output = AVCaptureMetadataOutput()
            self.session.addInput(input)
            self.session.addOutput(output)
            
            output.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)
            output.metadataObjectTypes = [AVMetadataObjectTypeFace]
//            output.rectOfInterest = CGRect(x: 135/ScreenHeight, y: (ScreenWidth-190)/(2*ScreenWidth), width: 240/ScreenHeight, height: 190/ScreenWidth)
            
            self.stillImageOutput.outputSettings = [AVVideoCodecKey: AVVideoCodecJPEG]
            self.session.addOutput(self.stillImageOutput)
            
            self.layer = AVCaptureVideoPreviewLayer(session: self.session)
            self.layer.videoGravity = AVLayerVideoGravityResizeAspectFill
            self.layer.frame = UIScreen.main.bounds
            
            self.view.layer.addSublayer(self.layer)
            self.session.startRunning()
        }catch {
            return
        }
        
    }
    
    func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [Any]!, from connection: AVCaptureConnection!) {
        if let meta = metadataObjects.first as? AVMetadataFaceObject {
            let a = self.layer.transformedMetadataObject(for: meta) as! AVMetadataFaceObject
            let faceRect = CGRect(x: a.bounds.origin.x-10, y: a.bounds.origin.y-10, width: a.bounds.size.width+20, height: a.bounds.size.height+20)
            if faceRect.origin.x <= 70 && faceRect.size.width >= ScreenWidth-140 {
                if self.timer == nil {
                    self.timer = Timer.scheduledTimer(timeInterval: 3, target: self, selector: #selector(ScanFaceViewController.isStop), userInfo: nil, repeats: false)
                    self.startUpdateView()
                }
            }
        }else {
            self.timer?.invalidate()
            self.timer = nil
            self.stopUpdateView()
        }
    }
    
    fileprivate func startUpdateView() {
        if self.timer != nil {
            self.label.text = "验证中"
            UIView.animate(withDuration: 0.2, animations: { 
                self.label.alpha = 0.2
            }, completion: { (finish) in
                UIView.animate(withDuration: 0.2, animations: { 
                    self.label.alpha = 1
                }, completion: { (finish) in
                    self.startUpdateView()
                })
            })
        }
    }
    
    fileprivate func stopUpdateView() {
        self.label.text = "等待验证"
        self.label.alpha = 1
    }
    
    @objc fileprivate func isStop() {
        self.timer?.invalidate()
        self.timer = nil
        self.catchImage()
        self.session.stopRunning()
    }
    
    @objc fileprivate func catchImage() {
        var imageConnection: AVCaptureConnection?
        for c in self.stillImageOutput.connections {
            let connection = c as! AVCaptureConnection
            for p in connection.inputPorts {
                let port = p as! AVCaptureInputPort
                if port.mediaType == AVMediaTypeVideo {
                    imageConnection = connection
                    break
                }
            }
            if let _ = imageConnection {
                break
            }
        }
        self.stillImageOutput.captureStillImageAsynchronously(from: imageConnection!, completionHandler: { (imageDataSampleBuffer, error) -> Void in
            if let bu = imageDataSampleBuffer {
                let imageData = AVCaptureStillImageOutput.jpegStillImageNSDataRepresentation(bu)
                let facePhoto = UIImage(data: imageData!)
                let formatter = DateFormatter()
                formatter.dateFormat = "yyyy-MM-dd HH:mm:ss"
                self.saveImage(image: facePhoto!, saveName: "\(formatter.string(from: Date()))")
            }
        })
    }
    
    fileprivate func saveImage(image: UIImage, saveName: String) {
        if let data = UIImageJPEGRepresentation(image, 0.8) {
            let fullPath = NSHomeDirectory().appending("/Documents").appending("/\(saveName)")
            NSData(data: data).write(toFile: fullPath, atomically: false)
        }
    }
}

用的是Swift3.0写的，如果没更新到最新的Swift，会报错