What is the front camera's deviceUniqueID? - ios

Question

I am trying to write an app that involves both front and rear camera and switching between them. As far as I understand, in the addVideoInput method, I have to change the IDs in
AVCaptureDevice *videoDevice = [AVCaptureDevice deviceWithUniqueID:(NSString *)deviceUniqueID];
But which NSStrings are those IDs?
Or, if it should be done in the other way, please, give a suggestion.
Thank you for help!

Answer 1

Ok, I have managed to find out a solution. I don't know if it's right or wrong, it was taken from http://www.bunnyhero.org/2010/08/15/turn-your-iphone-into-a-vampire-with-avfoundation-and-ios-4/
Just use
AVCaptureDevice *captureDevice = [self frontFacingCameraIfAvailable];
where frontFacingCameraIfAvailable is:
-(AVCaptureDevice *)frontFacingCameraIfAvailable
{
NSArray *videoDevices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
AVCaptureDevice *captureDevice = nil;
for (AVCaptureDevice *device in videoDevices)
{
if (device.position == AVCaptureDevicePositionFront)
{
captureDevice = device;
break;
}
}
// couldn't find one on the front, so just get the default video device.
if ( ! captureDevice)
{
captureDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
}
return captureDevice;
}

Answer 2

You can usually get frontal camera using
AVCaptureDevice *frontalCamera = [AVCaptureDevice deviceWithUniqueID:#"com.apple.avfoundation.avcapturedevice.built-in_video:1"];
But I would by all means rather use your accepted method - this one is not safe at all.

Answer 3

I was facing issue scanning QR Code with Front Camera. I looked out for so many resources and libraries in order to do so. Library was not fulfilling my requirement as I needed customised UI for scanner. And the piece of code on the internet to scan QR Code was also deprecated. So by debugging and knowing the device type I applied position of the camera and it worked. I am posting this as an answer so that it will help another peer like me looking for the answer.
- (void)viewDidLoad {
[super viewDidLoad];
// Do any additional setup after loading the view.
[self setupScanner];
[self openScanner:nil];
}
#pragma mark- Actions
- (IBAction)openScanner:(id)sender {
if([UIImagePickerController isCameraDeviceAvailable:UIImagePickerControllerCameraDeviceFront]){
[self.session startRunning];
}
}
- (IBAction)stopScanner:(id)sender {
[self.session stopRunning];
}
- (void)setupScanner {
#if !(TARGET_OS_SIMULATOR)
//self.device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
self.device = [self frontFacingCameraIfAvailable];
self.input = [AVCaptureDeviceInput deviceInputWithDevice:self.device error:nil];
self.session = [[AVCaptureSession alloc] init];
self.output = [[AVCaptureMetadataOutput alloc] init];
if([self.session canAddOutput:self.output]) {
[self.session addOutput:self.output];
}
if ([self.session canAddInput:self.input]){
[self.session addInput:self.input];
}
[self.output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
[self.output setMetadataObjectTypes:#[AVMetadataObjectTypeQRCode]];
self.preview = [AVCaptureVideoPreviewLayer layerWithSession:self.session];
self.preview.videoGravity = AVLayerVideoGravityResizeAspectFill;
self.preview.frame = CGRectMake(0, 0, CGRectGetWidth(self.pLayer.frame), CGRectGetHeight(self.pLayer.frame));
AVCaptureConnection *con = self.preview.connection;
con.videoOrientation = AVCaptureVideoOrientationLandscapeRight;
//pLayer is a UIView outlet on which the scanner fits or occupies its area to scan QR Code
[self.pLayer.layer insertSublayer:self.preview atIndex:0];
#endif
}
#pragma mark - AVCaptureMetadataOutputObjectsDelegate
- (void)captureOutput:(AVCaptureOutput *)output didOutputMetadataObjects:(NSArray<__kindof AVMetadataObject *> *)metadataObjects fromConnection:(AVCaptureConnection *)connection {
CGRect highlightViewRect = CGRectZero;
AVMetadataMachineReadableCodeObject *barCodeObject;
NSString *detectionString = nil;
NSArray *barCodeTypes = #[AVMetadataObjectTypeUPCECode, AVMetadataObjectTypeCode39Code, AVMetadataObjectTypeCode39Mod43Code,
AVMetadataObjectTypeEAN13Code, AVMetadataObjectTypeEAN8Code, AVMetadataObjectTypeCode93Code, AVMetadataObjectTypeCode128Code,
AVMetadataObjectTypePDF417Code, AVMetadataObjectTypeQRCode, AVMetadataObjectTypeAztecCode];
for (AVMetadataObject *metadata in metadataObjects) {
for (NSString *type in barCodeTypes) {
if ([metadata.type isEqualToString:type])
{
barCodeObject = (AVMetadataMachineReadableCodeObject *)[self.preview transformedMetadataObjectForMetadataObject:(AVMetadataMachineReadableCodeObject *)metadata];
highlightViewRect = barCodeObject.bounds;
detectionString = [(AVMetadataMachineReadableCodeObject *)metadata stringValue];
break;
}
}
if (detectionString != nil) {
self.codeLabel.text = detectionString;
[self stopScanner:nil];
//Do your work with QR Code String ---
break;
}
else
self.codeLabel.text = #"CODE";
}
}
#pragma mark- Capture Device
-(AVCaptureDevice *)frontFacingCameraIfAvailable {
AVCaptureDevice *captureDevice = [AVCaptureDevice defaultDeviceWithDeviceType:AVCaptureDeviceTypeBuiltInWideAngleCamera mediaType:AVMediaTypeVideo position:AVCaptureDevicePositionFront];
NSLog(#"capture device %#",captureDevice.description);
NSLog(#"device type %#",captureDevice.deviceType);
NSLog(#"unique Id: %#",captureDevice.uniqueID);
//com.apple.avfoundation.avcapturedevice.built-in_video:1
//Device Position: 2
NSLog(#"frontFacingCameraIfAvailable-> Device Position: %ld",(long)captureDevice.position);
return captureDevice;
}
-(AVCaptureDevice *)backFacingCameraIfAvailable {
AVCaptureDevice *captureDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
NSLog(#"capture device %#",captureDevice.description);
NSLog(#"device type %#",captureDevice.deviceType);
NSLog(#"unique Id: %#",captureDevice.uniqueID);
NSLog(#"backFacingCameraIfAvailable-> Device Position: %ld",(long)captureDevice.position);
return captureDevice;
}