Scanning Barcode or Qr Code in Swift 3.0 Using Avfoundation

Scanning Barcode or QR code in Swift 3.0 using AVFoundation

The first step needs to be declare access to any user private data types that is a new requirement in iOS 10. You can do it by adding a usage key to your app’s Info.plist together with a purpose string.

Because if you are using one of the following frameworks and fail to declare the usage your app will crash when it first makes the access:

Contacts, Calendar, Reminders, Photos, Bluetooth Sharing, Microphone, Camera, Location, Health, HomeKit, Media Library, Motion, CallKit, Speech Recognition, SiriKit, TV Provider.

To avoid the crash you need to add the suggested key to Info.plist:

And then the system shows the purpose string when asking the user to allow access:

For more information about it you can use this article:

• Privacy Settings in iOS 10

I have done a little modifications to your BarcodeViewController to make it work properly as you can see below:

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!)
       }
   }
}

One of the important points was to declare the global variables and start and stop the captureSession inside the viewWillAppear(:) and viewWillDisappear(:) methods. In your previous code I think it was not called at all as it never enter inside the method to process the barcode.

I hope this help you.

AVFoundation can't scan low-contrast QR code

I got it working with Zbar. Super easy to use, too. Here's a tiny demo (Xcode 9.3 and Swift 4.1): https://github.com/philipshen/ZBar-Demo-Swift-4

xcode avfoundation barcode sanner how to return type of scanned code

You can switch your metadataObject's type property and check which one you've got:

switch metadataObject.type {
case .qr:
      print("qrcode")
 case .code128:
      print("code128")
 default:
      print("other type")
}

Scan QR Code and open URL – Swift AVFoundation library

Swift 3.0

Optional Chaining:
Optional Chaining as an Alternative to Forced Unwrapping.

You can check scanned String is url,xml,JSON by optional chaining. For more go to apple document here

if let url = URL(string: result.value){ //check whether the string is URL
    if #available(iOS 10.0, *) {
        UIApplication.shared.open(url, options: [:], completionHandler: nil)
    } else {
        UIApplication.shared.openURL(url)
    }
}else {
    //do more if scanned text is not url string
}

Barcode on swift 4

I figured it out but Apple didn't make it so obvious. The callback function from the delegate AVCaptureMetadataOutputObjectsDelegate has been renamed and the parameter names are different!

So, replace

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

to

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

My view controller is now scanning QR Codes as before after this. It has the same parameters but the first parameter name is different. Change the function and parameter names and build/run.

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