Barcode Scanner in iOS

Question

I used the AV Foundation framework for the barcode scan feature.

session = [[AVCaptureSession alloc] init];
device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
NSError *error = nil;

input = [AVCaptureDeviceInput deviceInputWithDevice:device error:&error];
if (input) {
    [session addInput:input];
} else {
    NSLog(@"Error: %@", error);
}

output = [[AVCaptureMetadataOutput alloc] init];
[output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
[session addOutput:output];

output.metadataObjectTypes = [output availableMetadataObjectTypes];

prevLayer = [AVCaptureVideoPreviewLayer layerWithSession:session];
prevLayer.frame = self.view.bounds;

using the deletegete method, I get the result of the barcode. barcode number

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)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 *)[_prevLayer transformedMetadataObjectForMetadataObject:(AVMetadataMachineReadableCodeObject *)metadata];
                barcodeString = [(AVMetadataMachineReadableCodeObject *)metadata stringValue];
                break;
            }
        }

        if (barcodeString != nil)
        {
            NSLog(@"Barcode String: %@",barcodeString);
        }
        else
            label.text = @"(none)";
    }
}

Note: his work. but, the main reason, I do not get the barcode number always. please help me in this matter.

Answer 1

Your delegate method looks great, but you have to add: videoGravity to your AVCaptureVideoPreviewLayer (prevLayer) and start the session. Try adding these lines of code at the end of the first method:

prevLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
[self.view.layer addSublayer:prevLayer];  
[session startRunning];

Answer 2

I used this open source project to scan a barcode ..

: -

LINK: - https://github.com/jpwidmer/iOS7-BarcodeScanner

Answer 3

.m(implementation):

AVCaptureSession *_session;
AVCaptureDevice *_device;
AVCaptureDeviceInput *_input;
AVCaptureMetadataOutput *_output;
AVCaptureVideoPreviewLayer *_prevLayer;

UIView *_highlightView;
UILabel *_label;

( ):

-(void)readBarcode:(UIViewController*)myView
{ 
    _highlightView = [[UIView alloc] init];
    _highlightView.autoresizingMask = UIViewAutoresizingFlexibleTopMargin|UIViewAutoresizingFlexibleLeftMargin|UIViewAutoresizingFlexibleRightMargin|UIViewAutoresizingFlexibleBottomMargin;
    _highlightView.layer.borderColor = [UIColor greenColor].CGColor;
    _highlightView.layer.borderWidth = 3;
    [self.view addSubview:_highlightView];

    _label = [[UILabel alloc] init];
    _label.frame = CGRectMake(0, self.view.bounds.size.height - 40, self.view.bounds.size.width, 40);
    _label.autoresizingMask = UIViewAutoresizingFlexibleTopMargin;
    _label.backgroundColor = [UIColor colorWithWhite:0.15 alpha:0.65];
    _label.textColor = [UIColor whiteColor];
    _label.textAlignment = NSTextAlignmentCenter;
    _label.text = @"(none)";
    [self.view addSubview:_label];

    _session = [[AVCaptureSession alloc] init];
    _device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    NSError *error = nil;

    _input = [AVCaptureDeviceInput deviceInputWithDevice:_device error:&error];
    if (_input) {
        [_session addInput:_input];
    } else {
        NSLog(@"Error: %@", error);
    }

    _output = [[AVCaptureMetadataOutput alloc] init];
    [_output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
    [_session addOutput:_output];

    _output.metadataObjectTypes = [_output availableMetadataObjectTypes];

    _prevLayer = [AVCaptureVideoPreviewLayer layerWithSession:_session];
    _prevLayer.frame = self.view.bounds;
    _prevLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
    [self.view.layer addSublayer:_prevLayer];

    [_session startRunning];

    [self.view bringSubviewToFront:_highlightView];
    [self.view bringSubviewToFront:_label];
}

, , AVCaptureMetadataOutputObjectsDelegate:

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)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 *)[_prevLayer transformedMetadataObjectForMetadataObject:(AVMetadataMachineReadableCodeObject *)metadata];
                highlightViewRect = barCodeObject.bounds;
                detectionString = [(AVMetadataMachineReadableCodeObject *)metadata stringValue];
                break;
            }
        }
if (detectionString != nil)
        {
            _label.text = detectionString;
            break;
        }
        else
            _label.text = @"(none)";
    }

    _highlightView.frame = highlightViewRect;
}

Answer 4

post. , . - .

, , . , , -, DataMatrix.

detectionString , , .

Answer 5

In my case, I used serial queues and therefore ran into problems. Always use the main queue as shown below. [captureMetadataOutput setMetadataObjectsDelegate: self queue: dispatch_get_main_queue ()];