无法打开iOS相机

Question

I am trying to create a barcode reader feature for an app. For which I am not able to get any camera devices.

I am using AVCaptureDevice.DiscoverySession(deviceTypes: [.builtInDualCamera], mediaType: AVMediaType.video, position:. back) to get the list of devices.

I am trying to get the first device from the above list

But it does not returns any cameras.

I have also added a Privacy - Camera Usage Description in info.plist

       func viewDidLoad() {

            let deviceDiscoverySession = AVCaptureDevice.DiscoverySession(deviceTypes: [.builtInDualCamera], 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

            videoPreviewLayer = AVCaptureVideoPreviewLayer(session: captureSession!)

            videoPreviewLayer?.videoGravity = AVLayerVideoGravity.resizeAspectFill

            videoPreviewLayer?.frame = view.layer.bounds

            view.layer.addSublayer(videoPreviewLayer!)



            //Start video capture.

            captureSession?.startRunning()

        } catch {

            // if any error occurs, print it out and don't continue any more

            print(error)

            return

        }
}

I expect it to start a camera; however, it rather gives me following error:

2019-05-05 16:17:46.609442-0500 BarCode[964:302791] [MC] System group container for systemgroup.com.apple.configurationprofiles path is /private/var/containers/Shared/SystemGroup/systemgroup.com.apple.configurationprofiles

2019-05-05 16:17:46.609962-0500 BarCode[964:302791] [MC] Reading from public effective user settings.

Failed to get the camera device.

Answer 1

It could be just as the error mentions. There isn't any .builtInDualCamera option available for the device.

The type for common camera that you can try is

let deviceDiscoverySession = AVCaptureDevice.DiscoverySession(deviceTypes: [.builtInWideAngleCamera], mediaType: AVMediaType.video, position: .back)

If you really do require the .builtInDualCamera , you can follow as the Apple document suggested which is to implement an if...else check for a fallback plan.

Building a Camera App