Swift 4 - How to scan a QR Code [duplicate] - ios

Question

This question already has answers here:
Barcode on swift 4
(4 answers)
Closed 5 years ago.
I am trying to scan a QR code with my app (Swift 4, iOS 11) and I followed along with this tutorial: https://www.hackingwithswift.com/example-code/media/how-to-scan-a-barcode
But when I run my app, the camera does appear, but my method called captureOutput is not being called, I did some reason and I changed my that method from this:
func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [Any]!, from connection: AVCaptureConnection!)
to this
func captureOutput(captureOutput: AVCaptureOutput!, didOutputSampleBuffer sampleBuffer: CMSampleBuffer!, fromConnection connection: AVCaptureConnection!)
Still not being called. What Am I doing wrong?
Here is all my code:
import AVFoundation
import UIKit
class QRCode: UIViewController, AVCaptureMetadataOutputObjectsDelegate {
var captureSession: AVCaptureSession!
var previewLayer: AVCaptureVideoPreviewLayer!
override func viewDidLoad() {
super.viewDidLoad()
// Do any additional setup after loading the view, typically from a nib.
view.backgroundColor = UIColor.black
captureSession = AVCaptureSession()
guard let videoCaptureDevice = AVCaptureDevice.default(for: .video) else { return }
let videoInput: AVCaptureDeviceInput
do {
videoInput = try AVCaptureDeviceInput(device: videoCaptureDevice)
} catch {
return
}
if (captureSession.canAddInput(videoInput)) {
captureSession.addInput(videoInput)
} else {
failed()
return
}
let metadataOutput = AVCaptureMetadataOutput()
if (captureSession.canAddOutput(metadataOutput)) {
captureSession.addOutput(metadataOutput)
metadataOutput.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)
metadataOutput.metadataObjectTypes = [.ean8, .ean13, .pdf417]
} else {
failed()
return
}
previewLayer = AVCaptureVideoPreviewLayer(session: captureSession)
previewLayer.frame = view.layer.bounds
previewLayer.videoGravity = .resizeAspectFill
view.layer.addSublayer(previewLayer)
captureSession.startRunning()
}
func failed() {
let ac = UIAlertController(title: "Scanning not supported", message: "Your device does not support scanning a code from an item. Please use a device with a camera.", preferredStyle: .alert)
ac.addAction(UIAlertAction(title: "OK", style: .default))
present(ac, animated: true)
captureSession = nil
}
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()
}
}
override func didReceiveMemoryWarning() {
super.didReceiveMemoryWarning()
// Dispose of any resources that can be recreated.
}
func captureOutput(_ captureOutput: AVCaptureOutput!, didOutputMetadataObjects metadataObjects: [Any]!, from connection: AVCaptureConnection!) {
captureSession.stopRunning()
if let metadataObject = metadataObjects.first {
guard let readableObject = metadataObject as? AVMetadataMachineReadableCodeObject else { return }
guard let stringValue = readableObject.stringValue else { return }
AudioServicesPlaySystemSound(SystemSoundID(kSystemSoundID_Vibrate))
found(code: stringValue)
}
dismiss(animated: true)
}
func found(code: String) {
print(code)
}
override var prefersStatusBarHidden: Bool {
return true
}
override var supportedInterfaceOrientations: UIInterfaceOrientationMask {
return .portrait
}
}

Answer 1

Have you put into info.plist the camera permissions?
<key>NSCameraUsageDescription</key>
<string>Camera is required to use this application</string>