ios - 扫描成功后 AVFoundation 停止

Question

我正在使用 Swift 3(Xcode 8.1) 为 iOS 10 构建一个 QR 码扫描仪应用程序，并且我正在使用 AVFoundation 框架。有谁知道如何在成功扫描后停止扫描并在点击屏幕等操作后重新激活扫描仪？

编辑: 这是我的代码片段(没有返回值发生的情况的代码):

import UIKit
import AVFoundation

@available(iOS 10.0, *)
class QRCodeViewController: UIViewController, AVCaptureMetadataOutputObjectsDelegate {
var captureSession:AVCaptureSession?
var videoPreviewLayer:AVCaptureVideoPreviewLayer?
var qrCodeFrameView:UIView?

let supportedBarCodes = [AVMetadataObjectTypeQRCode, AVMetadataObjectTypeCode128Code, AVMetadataObjectTypeCode39Code, AVMetadataObjectTypeCode93Code, AVMetadataObjectTypeUPCECode, AVMetadataObjectTypePDF417Code, AVMetadataObjectTypeEAN13Code, AVMetadataObjectTypeAztecCode]

override func viewDidLoad() {
    super.viewDidLoad()

let captureDevice = AVCaptureDevice.defaultDevice(withMediaType: AVMediaTypeVideo)

    do {
        let input = try AVCaptureDeviceInput(device: captureDevice)

        captureSession = AVCaptureSession()
        captureSession?.addInput(input)

        let captureMetadataOutput = AVCaptureMetadataOutput()
        captureSession?.addOutput(captureMetadataOutput)

        captureMetadataOutput.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)

        captureMetadataOutput.metadataObjectTypes = supportedBarCodes

        videoPreviewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
        videoPreviewLayer?.videoGravity = AVLayerVideoGravityResizeAspectFill
        videoPreviewLayer?.frame = view.layer.bounds
        view.layer.addSublayer(videoPreviewLayer!)

        captureSession?.startRunning()


        qrCodeFrameView = UIView()

        if case (qrCodeFrameView?.isHidden)! = true       {
            qrCodeFrameView?.layer.borderColor = UIColor.green.cgColor
            qrCodeFrameView?.layer.borderWidth = 2
            view.addSubview(qrCodeFrameView!)
            view.bringSubview(toFront: qrCodeFrameView!)
        }

    } catch {
        print(error)
        return
    }

}

override var supportedInterfaceOrientations : UIInterfaceOrientationMask {
    return UIInterfaceOrientationMask.portrait
}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()

}

func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [Any]!, from connection: AVCaptureConnection!) {

    if metadataObjects == nil || metadataObjects.count == 0 {
        qrCodeFrameView?.frame = CGRect.zero
        return
    }




    let metadataObj = metadataObjects[0] as! AVMetadataMachineReadableCodeObject


    if supportedBarCodes.contains(metadataObj.type) {

        let barCodeObject = videoPreviewLayer?.transformedMetadataObject(for: metadataObj)
        qrCodeFrameView?.frame = barCodeObject!.bounds
  print(metadataObj.stringValue)

}

Answer 1

在您的委托(delegate)方法中尝试此操作

func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [Any]!, from connection: AVCaptureConnection!) {

if metadataObjects == nil || metadataObjects.count == 0 {
    qrCodeFrameView?.frame = CGRect.zero
    return
}

let metadataObj = metadataObjects[0] as! AVMetadataMachineReadableCodeObject


if supportedBarCodes.contains(metadataObj.type) {

    let barCodeObject = videoPreviewLayer?.transformedMetadataObject(for: metadataObj)
    qrCodeFrameView?.frame = barCodeObject!.bounds
    print(metadataObj.stringValue)

    // Stop capture session 
    videoPreviewLayer?.isHidden = true
    qrCodeFrameView?.isHidden = true
    self.captureSession?.stopRunning()
}