Why is barcode scanning using the new iOS 7 API so slow?

Question

I'm currently trying to use iOS 7 latest api to scan the barcodes of code 39, but it drives me crazy. I have to keep the phone in a certain order, still like 10 seconds, so that it can detect it. I compared it with Red Laser, Zbar, etc., And they could analyze it in 1 second, even if it is slightly distorted. I'm not sure if this is due to how I load the capture session or what. I would appreciate help. Any suggestions on how to improve performance?

This is how I load the scanner into my viewDidLoad method:

    //Initialize Laser View
    laserView = [[UIView alloc] init];
    laserView.autoresizingMask = UIViewAutoresizingFlexibleTopMargin|UIViewAutoresizingFlexibleLeftMargin|UIViewAutoresizingFlexibleRightMargin|UIViewAutoresizingFlexibleBottomMargin;
    laserView.layer.borderColor = [UIColor redColor].CGColor;
    laserView.layer.borderWidth = 8;
    laserView.layer.cornerRadius = 10;
    [self.view addSubview:laserView];

    //Start Session
    scannerSession = [[AVCaptureSession alloc] init];
    scannerDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

    //Define Error Messages
    NSError *error = nil;

    //Define Input
    scannerInput = [AVCaptureDeviceInput deviceInputWithDevice:scannerDevice error:&error];

    //Check if Device has a Camera
    if (scannerInput) {
        [scannerSession addInput:scannerInput];
    } else {
        NSLog(@"Error: %@", error);
    }

    // Locks the configuration
    BOOL success = [scannerDevice lockForConfiguration:nil];
    if (success) {
        if ([scannerDevice isAutoFocusRangeRestrictionSupported]) {

            // Restricts the autofocus to near range (new in iOS 7)
            [scannerDevice setAutoFocusRangeRestriction:AVCaptureAutoFocusRangeRestrictionNear];
        }
    }
    // unlocks the configuration
    [scannerDevice unlockForConfiguration];

    //Define Output & Metadata Object Types
    scannerOutput = [[AVCaptureMetadataOutput alloc] init];
    [scannerOutput setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
    [scannerSession addOutput:scannerOutput];
    scannerOutput.metadataObjectTypes = [scannerOutput availableMetadataObjectTypes];

    //Create Video Preview Layer
    scannerPreviewLayer = [AVCaptureVideoPreviewLayer layerWithSession:scannerSession];
    scannerPreviewLayer.frame = self.view.bounds;
    scannerPreviewLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
    [self.view.layer addSublayer:scannerPreviewLayer];

    //Start Session
    [scannerSession startRunning];
    [self.view bringSubviewToFront:cancelButton];
    [self.view bringSubviewToFront:laserView];

and

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

    //Prepare Laser View
    CGRect laser = CGRectZero;

    //Format Date
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:@"M/d"];

    //Format Time
    NSDateFormatter *timeFormatter = [[NSDateFormatter alloc] init];
    [timeFormatter setDateFormat:@"h:ma"];

    //Define Barcode Types to Recognize
    AVMetadataMachineReadableCodeObject *barCodeObject;
    NSString *idNumber = nil;
    NSArray *barCodeTypes = @[AVMetadataObjectTypeCode39Code];

    if ([metadataObjects count] > 1) {

        NSLog(@"%lu Barcodes Found.", (unsigned long)[metadataObjects count]);

    }

    //Get String Value For Every Barcode (That Matches The Type We're Looking For)
    for (AVMetadataObject *metadata in metadataObjects) {


        for (NSString *type in barCodeTypes) {


            //If The Barcode Is The Type We Need Then Get Data
            if ([metadata.type isEqualToString:type]) {

                barCodeObject = (AVMetadataMachineReadableCodeObject *)[scannerPreviewLayer transformedMetadataObjectForMetadataObject:(AVMetadataMachineReadableCodeObject *)metadata];
                laser = barCodeObject.bounds;
                idNumber = [(AVMetadataMachineReadableCodeObject *)metadata stringValue];
                break;
            }
        }

        // If IDNumber Found
        if (idNumber != nil) {

            //Stop Session
            [scannerSession stopRunning];
            [self vibrate];

            NSLog(@"ID: %@", idNumber);

            break;
        }

        //If IDNumber Is Not Found
        else {

            NSLog(@"No ID Found.");
        }
    }

    //Update Laser
    laserView.frame = laser;
}

Answer 1

... videoDevice.videoZoomFactor = 2.0;

Answer 2

(, , ..). , .

Answer 3

NSLog captureOutput:

, - . NSDateFormatter - NSDateFormatter "" ?.

, NSDateFormatter , , . .

Answer 4

I had a similar problem with AVCaptureSession, the capture was very slow, and sometimes it took a long time to complete it.

I don’t know if my solution is suitable for you, but it can definitely be useful for someone else looking for this problem, just like me.

AVCaptureSession *captureSession = [AVCaptureSession new];
captureSession.sessionPreset = AVCaptureSessionPresetHigh;

With this code, you force the camera to a high-quality preset.

Hope this helps someone.