ios - 成功扫描后 AVFoundation 停止

Question

我正在使用适用于 iOS 10 的 Swift 3(Xcode 8.1) 构建二维码扫描器应用程序，并且我正在使用 AVFoundation 框架。有人知道如何在成功扫描后停止扫描并在点击屏幕或其他操作后重新激活扫描器吗？

编辑:这是我的代码片段(没有关于返回值的代码):

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

在你的委托(delegate)方法中试试这个

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()
}