Question

我正在关注此tutorial并尝试将代码从Swift 2.0转换为3.0。但是当我启动应用程序时，该应用程序无法正常工作！我的意思是，没有任何反应这是我的代码：

的ViewController：

class ViewController: UIViewController ,BarcodeDelegate {

    override func prepare(for segue: UIStoryboardSegue, sender: Any?) {

        let barcodeViewController: BarcodeViewController = segue.destination as! BarcodeViewController
        barcodeViewController.delegate = self

    }



    func barcodeReaded(barcode: String) {
        codeTextView.text = barcode
        print(barcode)
    }

}

BarcodeVC：

import AVFoundation


protocol BarcodeDelegate {

    func barcodeReaded(barcode: String)
}

class BarcodeViewController: UIViewController,AVCaptureMetadataOutputObjectsDelegate {

    var delegate: BarcodeDelegate?
    var captureSession: AVCaptureSession!
    var code: String?


    override func viewDidLoad() {
        super.viewDidLoad()

        // Do any additional setup after loading the view.
        print("works")

        self.captureSession = AVCaptureSession();
        let videoCaptureDevice: AVCaptureDevice = AVCaptureDevice.defaultDevice(withMediaType: AVMediaTypeVideo)

        do {

            let videoInput = try AVCaptureDeviceInput(device: videoCaptureDevice)

            if self.captureSession.canAddInput(videoInput) {
                self.captureSession.addInput(videoInput)
            } else {
                print("Could not add video input")
            }

            let metadataOutput = AVCaptureMetadataOutput()
            if self.captureSession.canAddOutput(metadataOutput) {
                self.captureSession.addOutput(metadataOutput)

                metadataOutput.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)
                metadataOutput.metadataObjectTypes = [AVMetadataObjectTypeQRCode,AVMetadataObjectTypeEAN8Code, AVMetadataObjectTypeEAN13Code, AVMetadataObjectTypePDF417Code]
            } else {
                print("Could not add metadata output")
            }

            let previewLayer = AVCaptureVideoPreviewLayer(session: self.captureSession)
            previewLayer?.frame = self.view.layer.bounds
            self.view.layer .addSublayer(previewLayer!)
            self.captureSession.startRunning()
        } catch let error as NSError {
            print("Error while creating vide input device: \(error.localizedDescription)")
        }



    }



    //I THINK THIS METHOD NOT CALL !
    private func captureOutput(captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [AnyObject]!, fromConnection connection: AVCaptureConnection!) {

        // This is the delegate'smethod that is called when a code is readed
        for metadata in metadataObjects {
            let readableObject = metadata as! AVMetadataMachineReadableCodeObject
            let code = readableObject.stringValue

            // If the code is not empty the code is ready and we call out delegate to pass the code.
            if  code!.isEmpty {
                print("is empty")

            }else {

                self.captureSession.stopRunning()
                self.dismiss(animated: true, completion: nil)
                self.delegate?.barcodeReaded(barcode: code!)


            }
        }

    }

这是输出：

2016-09-17 18：10：26.000919 BarcodeScaning [2610：674253] [MC] systemgroup.com.apple.configurationprofiles路径的系统组容器是/ private / var / containers / Shared /SystemGroup/systemgroup.com.apple.configurationprofiles 2016-09-17 18：10：26.007782 BarcodeScaning [2610：674253] [MC] 从公共有效用户设置中读取。

Answer 1

第一步需要声明对iOS 10中新要求的任何用户私有数据类型的访问权限。您可以通过向应用程序的Info.plist添加使用密钥以及目的字符串来实现。

因为如果您使用以下框架之一并且未能声明其使用情况，您的应用在首次访问时将崩溃：

通讯录，日历，提醒，照片，蓝牙共享，麦克风，相机，位置，健康，HomeKit，媒体库，动作，CallKit，语音识别，SiriKit，电视提供商。

为避免崩溃，您需要将建议的密钥添加到Info.plist：

然后系统在要求用户允许访问时显示目的字符串：

有关它的更多信息，您可以使用本文：

Privacy Settings in iOS 10

我已对您的BarcodeViewController做了一些修改，以使其正常工作，如下所示：

<强> BarcodeViewController

import UIKit
import AVFoundation

protocol BarcodeDelegate {
   func barcodeReaded(barcode: String)
}

class BarcodeViewController: UIViewController, AVCaptureMetadataOutputObjectsDelegate {

   var delegate: BarcodeDelegate?

   var videoCaptureDevice: AVCaptureDevice = AVCaptureDevice.defaultDevice(withMediaType: AVMediaTypeVideo)
   var device = AVCaptureDevice.defaultDevice(withMediaType: AVMediaTypeVideo)
   var output = AVCaptureMetadataOutput()
   var previewLayer: AVCaptureVideoPreviewLayer?

   var captureSession = AVCaptureSession()
   var code: String?

   override func viewDidLoad() {
      super.viewDidLoad()

      self.view.backgroundColor = UIColor.clear
      self.setupCamera()
   }

   private func setupCamera() {

      let input = try? AVCaptureDeviceInput(device: videoCaptureDevice)

      if self.captureSession.canAddInput(input) {
          self.captureSession.addInput(input)
      }

      self.previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)

      if let videoPreviewLayer = self.previewLayer {
          videoPreviewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill
          videoPreviewLayer.frame = self.view.bounds
          view.layer.addSublayer(videoPreviewLayer)
      }

      let metadataOutput = AVCaptureMetadataOutput()
      if self.captureSession.canAddOutput(metadataOutput) {
          self.captureSession.addOutput(metadataOutput)

          metadataOutput.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)
          metadataOutput.metadataObjectTypes = [AVMetadataObjectTypeQRCode, AVMetadataObjectTypeEAN13Code]
      } else {
          print("Could not add metadata output")
      }
   }

   override func viewWillAppear(_ animated: Bool) {
       super.viewWillAppear(animated)

       if (captureSession.isRunning == false) {
          captureSession.startRunning();
       }
   }

   override func viewWillDisappear(_ animated: Bool) {
      super.viewWillDisappear(animated)

      if (captureSession.isRunning == true) {
         captureSession.stopRunning();
      }
   }

   func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [Any]!, from connection: AVCaptureConnection!) {
       // This is the delegate's method that is called when a code is read
       for metadata in metadataObjects {
           let readableObject = metadata as! AVMetadataMachineReadableCodeObject
           let code = readableObject.stringValue


           self.dismiss(animated: true, completion: nil)
           self.delegate?.barcodeReaded(barcode: code!)
           print(code!)
       }
   }
}

其中一个重点是声明全局变量并在captureSession和viewWillAppear(:)方法中启动和停止viewWillDisappear(:)。在您之前的代码中，我认为它根本没有被调用，因为它从不进入处理条形码的方法内。

我希望这对你有所帮助。

Answer 2

以下Victor Sigler's answer更新为 Swift 4 ，无需强制解包，弱协议，在后台线程中执行昂贵的代码以及其他改进。

请注意，AVCaptureMetadataOutputObjectsDelegate的方法已从

更改

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

到

metadataOutput(_ output: AVCaptureMetadataOutput, didOutput metadataObjects: [AVMetadataObject], from connection: AVCaptureConnection)

import UIKit
import AVFoundation

protocol BarcodeDelegate: class {
    func barcodeRead(barcode: String)
}

class ScannerViewController: UIViewController, AVCaptureMetadataOutputObjectsDelegate {
    weak var delegate: BarcodeDelegate?

    var output = AVCaptureMetadataOutput()
    var previewLayer: AVCaptureVideoPreviewLayer!

    var captureSession = AVCaptureSession()

    override func viewDidLoad() {
        super.viewDidLoad()

        setupCamera()
    }

    override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)

        DispatchQueue.global(qos: .background).async {
            if !self.captureSession.isRunning {
                self.captureSession.startRunning()
            }
        }
    }

    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)

        DispatchQueue.global(qos: .background).async {
            if self.captureSession.isRunning {
                self.captureSession.stopRunning()
            }
        }
    }

    fileprivate func setupCamera() {
        guard let device = AVCaptureDevice.default(for: .video),
            let input = try? AVCaptureDeviceInput(device: device) else {
            return
        }

        DispatchQueue.global(qos: .background).async {
            if self.captureSession.canAddInput(input) {
                self.captureSession.addInput(input)
            }

            let metadataOutput = AVCaptureMetadataOutput()

            if self.captureSession.canAddOutput(metadataOutput) {
                self.captureSession.addOutput(metadataOutput)

                metadataOutput.setMetadataObjectsDelegate(self, queue: .global(qos: .background))

                if Set([.qr, .ean13]).isSubset(of: metadataOutput.availableMetadataObjectTypes) {
                    metadataOutput.metadataObjectTypes = [.qr, .ean13]
                }
            } else {
                print("Could not add metadata output")
            }

            self.previewLayer = AVCaptureVideoPreviewLayer(session: self.captureSession)
            self.previewLayer.videoGravity = .resizeAspectFill

            DispatchQueue.main.async {
                self.previewLayer.frame = self.view.bounds
                self.view.layer.addSublayer(self.previewLayer)
            }
        }
    }

    func metadataOutput(_ output: AVCaptureMetadataOutput, didOutput metadataObjects: [AVMetadataObject], from connection: AVCaptureConnection) {
        // This is the delegate's method that is called when a code is read
        for metadata in metadataObjects {
            if let readableObject = metadata as? AVMetadataMachineReadableCodeObject,
                let code = readableObject.stringValue {
                dismiss(animated: true)
                delegate?.barcodeRead(barcode: code)
                print(code)
            }
        }
    }
}

Answer 3

Swift 4中的条码扫描器适用于所有代码类型

下面我想根据iOS中的条形码扫描分享一些想法。

从View逻辑中分离条形码扫描器逻辑，
在.plist文件中添加条目
设置exposurePointOfInterest和focusPointOfInterest
使用正确转换的CGRect设置rectOfInterests
设置focusMode和exposureMode
在更改摄像头捕获设置时正确锁定captureDevice lockForConfiguration

在.plist文件中添加条目
在Info.plist文件中添加以下代码以允许您的应用程序访问iPhone的摄像头：

<key>NSCameraUsageDescription</key>
<string>Allow access to camera</string>

设置exposurePointOfInterest和focusPointOfInterest
exposurePointOfInterest和focusPointOfInterest可以提高扫描质量，将相机更快地聚焦在屏幕的中心点。

设置rectOfInterests
此属性使相机可以仅关注屏幕的一部分。这样，代码可以更快地扫描，只关注屏幕中心显示的代码 - 在背景中可用的其他代码很少时有用。

设置focusMode和exposureMode 属性应设置如下：

device.focusMode = .continuousAutoFocus
device.exposureMode = .continuousAutoExposure

这样可以连续对焦并将曝光设置为扫描码。

演示

在这里你可以找到实现这个想法的现成项目： https://github.com/lukszar/QuickScanner

Answer 4

您需要将NSCameraUsageDescription添加到Info.plist文件中才能使其正常工作！

只需在 info.plist 中添加一行，然后在新创建的行中输入 NSCameraUsageDescription ，然后添加字符串用于通知用户为什么在您的应用程序中需要访问相机。

这应该可以解决问题！

Answer 5

func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [Any]!, from connection: AVCaptureConnection!) {
  print("caught QR code")
  for metadata in metadataObjects {
     let readableObject = metadata as! AVMetadataMachineReadableCodeObject
     let code = readableObject.stringValue
     if  code!.isEmpty {
        print("is empty")
     } else {
        self.captureSession.stopRunning()
        self.dismiss(animated: true, completion: nil)
        self.delegate?.gotQRCode(code: code!)
     }
  }
}

看起来该方法的签名在Swift 3中有所改变。这是正确的版本

使用AVFoundation在Swift 3.0中扫描条形码或QR码

5 个答案:

Swift 4中的条码扫描器适用于所有代码类型

演示