Unsupported type found - AVMetadataObject

Question

I'm trying to implement barcode scanning in my iOS app, but for some reason I can't open the camera. I'm using Apple's AVFoundation framework for scanning.

This is my code for launching the camera and implement the scanner:

// Get the back-facing camera for capturing videos
let deviceDiscoverySession = AVCaptureDevice.DiscoverySession(deviceTypes: [.builtInWideAngleCamera], mediaType: AVMediaType.video, position: .back)

guard let captureDevice = deviceDiscoverySession.devices.first else {
    print("Failed to get the camera device")
    return
}

do {
    // Get an instance of the AVCaptureDeviceInput class using the previous device object.
    let input = try AVCaptureDeviceInput(device: captureDevice)

    // Set the input device on the capture session.
    captureSession?.addInput(input)

    // Initialize a AVCaptureMetadataOutput object and set it as the output device to the capture session.
    let captureMetadataOutput = AVCaptureMetadataOutput()
        captureSession?.addOutput(captureMetadataOutput)

    // Set delegate and use the default dispatch queue to execute the call back
    captureMetadataOutput.setMetadataObjectsDelegate(self, queue: DispatchQueue.main)
    captureMetadataOutput.metadataObjectTypes = [AVMetadataObject.ObjectType.qr]

    // Initialize the video preview layer and add it as a sublayer to the viewPreview view's layer.
    videoPreviewLayer = AVCaptureVideoPreviewLayer(session: captureSession!)
    videoPreviewLayer?.videoGravity = AVLayerVideoGravity.resizeAspectFill
    videoPreviewLayer?.frame = view.layer.bounds
    view.layer.addSublayer(videoPreviewLayer!)

    // Start video capture.
    captureSession?.startRunning()

    // Initialize QR Code Frame to highlight the QR code
    qrCodeFrameView = UIView()

    if let qrCodeFrameView = qrCodeFrameView {
        qrCodeFrameView.layer.borderColor = UIColor.green.cgColor
        qrCodeFrameView.layer.borderWidth = 2
        view.addSubview(qrCodeFrameView)
        view.bringSubview(toFront: qrCodeFrameView)
    }
} catch {
    // If any error occurs, simply print it out and don't continue any more.
    print(error)
    return
}

Immediately as the screen loads, I get the following message printed to the console:

*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '*** -[AVCaptureMetadataOutput setMetadataObjectTypes:] Unsupported type found - use -availableMetadataObjectTypes'
*** First throw call stack:
(0x1824d2d8c 0x18168c5ec 0x18803eb44 0x1013f035c 0x1013f12ec 0x18c23e64c 0x18c35f870 0x18c244700 0x18c37a1a8 0x18c2c19e0 0x18c2b6890 0x18c2b51d0 0x18ca96d1c 0x18ca992c8 0x18ca92368 0x18247b404 0x18247ac2c 0x18247879c 0x182398da8 0x18437d020 0x18c3b5758 0x1013da1d8 0x181e29fc0)
libc++abi.dylib: terminating with uncaught exception of type NSException
(lldb) 

I couldn't find any solution on Stack Overflow or on any other website.

Could you please help me fixing this?

Answer 1

So I had the same error and I solved it by making small changes. Hope this helps(if you haven't resolved it already!).

    let input = try AVCaptureDeviceInput(device: captureDevice)

    //Make sure you have initialized the captureSession object
        captureSession = AVCaptureSession()
        captureSession?.addInput(input)

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

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


       // Main Change
        captureMetadataOutput.metadataObjectTypes = captureMetadataOutput.availableMetadataObjectTypes
            //[AVMetadataObject.ObjectType.qr]

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


        captureSession?.startRunning()