Barcode Scanner in iOS - ios

Question

I Used AV Foundation framework for barcode scanning functionality.
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 delegete method i will get barcode result. i.e 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: its working. but, the main reason, i'm not getting barcode number always. will you please help me for this issue.

Answer 1

Your delegate method looks fine, but you should add: videoGravity to your AVCaptureVideoPreviewLayer (prevLayer) and get the session started. Try adding these lines of code in the end of your first method:
prevLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
[self.view.layer addSublayer:prevLayer];
[session startRunning];

Answer 2

I have used this open source project for Barcode scanning..
it will surely help you:-
LINK:- https://github.com/jpwidmer/iOS7-BarcodeScanner

Answer 3

Declare these objects in your .m (implementation) file:
AVCaptureSession *_session;
AVCaptureDevice *_device;
AVCaptureDeviceInput *_input;
AVCaptureMetadataOutput *_output;
AVCaptureVideoPreviewLayer *_prevLayer;
UIView *_highlightView;
UILabel *_label;
then add this method (which will be called by you):
-(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];
}
and finally add the 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

Just have a look at this post. You should read it carefully and also check the apple docs. And you can dowload the sample project from that post.
I do not know what problem you are facing exactly because your code looks fine. And may be the problem is you are scanning unsupportable barcodes like DataMatrix.
Please log your detectionString and see if every time you are getting value.

Answer 5

In my Case i was using serial queues and hence was facing problems .
Always use Main queue like below
[captureMetadataOutput setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];