QR image not detected by CIDetector

Question

I am developing an app where I have displayed the detected data from a QR code but the problem is that QR code is not detected. I have used this code:

NSDictionary *detectorOptions = @{ CIDetectorAccuracy : CIDetectorAccuracyHigh };
                CIDetector *faceDetector = [CIDetector detectorOfType:CIDetectorTypeQRCode context:nil options:detectorOptions];
                NSArray *features = [faceDetector featuresInImage:chosenImage.CIImage];
                CIQRCodeFeature *faceFeature;
                for(faceFeature in features)
                {
                    qrcodedetected = YES;
                    self.decodedstr = [NSString stringWithFormat:@"%@",faceFeature.messageString];
                    break;
                }

I have searched a lot but not succeeded. I have used this code from Apple default form. Every time I will get nil in result. If anybody has any solution regarding this then please share with me. It would be appreciated. Thanks in advance.

Answer 1

// initialize        
AVCaptureDevice *captureDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:captureDevice error:&error];

// create session
AVCaptureMetadataOutput *captureMetadataOutput = [[AVCaptureMetadataOutput alloc] init];
dispatch_queue_t dispatchQueue = dispatch_queue_create("QRCodeQueue", NULL);
[captureMetadataOutput setMetadataObjectsDelegate:self queue:dispatchQueue];
[captureMetadataOutput setMetadataObjectTypes:[captureMetadataOutput availableMetadataObjectTypes]];
[self.captureSession addOutput:captureMetadataOutput];

// add camera view layer
AVCaptureVideoPreviewLayer *captureLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:self.captureSession];
[captureLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];
[captureLayer setFrame:self.view.layer.bounds];
[self.view.layer addSublayer:captureLayer];

// delegate method
- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection {

  // Specify the barcodes you want to read here:
  NSArray *supportedBarcodeTypes = @[AVMetadataObjectTypeUPCECode, AVMetadataObjectTypeCode39Code, AVMetadataObjectTypeCode39Mod43Code, AVMetadataObjectTypeEAN13Code, AVMetadataObjectTypeEAN8Code, AVMetadataObjectTypeCode93Code, AVMetadataObjectTypeCode128Code, AVMetadataObjectTypePDF417Code, AVMetadataObjectTypeQRCode, AVMetadataObjectTypeAztecCode];

  for (AVMetadataObject *barcodeMetadata in metadataObjects) {
      for (NSString *supportedBarcode in supportedBarcodeTypes) {
         if ([supportedBarcode isEqualToString:barcodeMetadata.type]) {
             // get barcode object AVMetadataMachineReadableCodeObject
             AVMetadataMachineReadableCodeObject *barcodeObject = (AVMetadataMachineReadableCodeObject *)[self.captureLayer transformedMetadataObjectForMetadataObject:barcodeMetadata];
             NSString *capturedBarcode = [barcodeObject stringValue];
             // do what you want...
         }
      }
    }
}