QR Reader for iPhone

Question

So i need to write a QR reader for an iphone application. Usually frameworks like ZXING and ZBAr allow you to download an application and then read the barcode. I want to integrate it within the application itself. So basically i want to be able to tap a button and have it reading the QR code. Is this possible? If so are there any proper documentation on this? I tried using ZXing but when i link binaries libZXingWidget.a is unavailable. Also the documentation is not enough to know how to integrate it within the application. So let me know.

Answer 1

Here's code to setup ZBar, make sure to add the SDK to your project and link your library.

-

(void)viewDidLoad
{
        [ZBarReaderView class];
        readerView.readerDelegate = self;
        readerView.tracksSymbols = NO;

            //CHOOSE CAMERA
            if (some setting isEqual to CameraRear) {
                readerView.device = [self backFacingCameraIfAvailable];
            }
            else {
                readerView.device = [self frontFacingCameraIfAvailable];
            }

        [self relocateReaderPopover:[self interfaceOrientation]];
        [readerView start];
    }

-(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;
}

-(AVCaptureDevice *)backFacingCameraIfAvailable
{
    NSArray *videoDevices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
    AVCaptureDevice *captureDevice = nil;
    for (AVCaptureDevice *device in videoDevices)
    {
        if (device.position == AVCaptureDevicePositionBack)
        {
            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;
}

-(void)relocateReaderPopover:(UIInterfaceOrientation)toInterfaceOrientation{
    if (toInterfaceOrientation == UIInterfaceOrientationLandscapeLeft) {
        readerView.previewTransform = CGAffineTransformMakeRotation(M_PI_2);
    } else if (toInterfaceOrientation == UIInterfaceOrientationLandscapeRight) {
        readerView.previewTransform = CGAffineTransformMakeRotation(-M_PI_2);
    } else if (toInterfaceOrientation== UIInterfaceOrientationPortraitUpsideDown) {
        readerView.previewTransform = CGAffineTransformMakeRotation(M_PI);
    } else {
        readerView.previewTransform = CGAffineTransformIdentity;
    }
}

Answer 2

Once you have ZXing set up correctly the code to get a QR reader is literally this easy:

Make sure to import these two guys for QR:

#import "ZXingWidgetController.h"
#import "QRCodeReader.h"

Then in your controller you will set up the code reader as follows:

ZXingWidgetController *widController = [[ZXingWidgetController alloc] initWithDelegate:self showCancel:YES OneDMode:NO];

QRCodeReader *qrcodeReader = [[QRCodeReader alloc] init];

NSSet *readers = [[NSSet alloc] initWithObjects:qrcodeReader,nil];

widController.readers = readers;

[self presentModalViewController:widController animated:YES];

You basically set up the controller that handles the code reading (ZXingWidgetController) and then give it a set of all the types of code readers you want (here I just used QRCodeReader.) Lastly, you just present it as a modal view controller.

Then you will need to implement the <ZXingDelegate> and the following delegate functions:

- (void)zxingController:(ZXingWidgetController*)controller didScanResult:(NSString *)result
{  
    [self dismissModalViewControllerAnimated:YES];
    NSLog(@"%@",result);  //Simple NSString result.
}

- (void)zxingControllerDidCancel:(ZXingWidgetController*)controller
{
    [self dismissModalViewControllerAnimated:YES];
    NSLog(@"Cancelled");
}

The hardest part is just setting it up. I found this tutorial to be the most helpful (Sorry that I am using a link): How to install ZXing in Xcode 4 The comments are also helpful if you have any problems.

Answer 3

I have managed to integrate ZXING into my test project. I have done this a little time ago so I might not remember all the problems that I faced and solved. Into my workspace folder I have copied ZXing-2.0 folder. Inside I have only left folders: cpp, docs and iphone. To my workspace (containing the test project) I have added ZXingWidget project from the folder ZXing-2.0. This allowed me to add to linking setting libZXingWidget.a. When I build my test project, XCode detects dependency and builds the widget first and then builds the test project and links it against libZXingWidget.a.

Here's a simple view controller that I have implemented to display inside camera view able to detect QR code.

//
//  MyVC.m
//
//

#import "MyVC.h"
#import "QRCodeReader.h"

@interface MyVC () {
    ZXingWidgetController *_widController;
}

@end

@implementation MyVC

@synthesize labelResultString;

- (void)viewDidLoad {
    [super viewDidLoad];
    // Do any additional setup after loading the view from its nib.

    _widController = [[ZXingWidgetController alloc] initWithDelegate:(id<ZXingDelegate>)self showCancel:YES OneDMode:NO];
    QRCodeReader* qrcodeReader = [[QRCodeReader alloc] init];
    NSSet *readers = [[NSSet alloc ] initWithObjects:qrcodeReader,nil];
    //[qrcodeReader release];
    _widController.readers = readers;
    //[readers release];
    //NSBundle *mainBundle = [NSBundle mainBundle];
    //_widController.soundToPlay = [NSURL fileURLWithPath:[mainBundle pathForResource:@"beep-beep" ofType:@"aiff"] isDirectory:NO];
    _widController.overlayView.displayedMessage = @"";
    _widController.wantsFullScreenLayout = NO;

    //[self presentModalViewController:_widController animated:NO];
    _widController.view.frame = CGRectMake(10, 10, 300, 300);//self.view.frame;
    _widController.view.autoresizingMask = UIViewAutoresizingNone;
    _widController.overlayView.frame = CGRectMake(0, 0, 300, 300);
    _widController.overlayView.cropRect = CGRectMake(20, 20, 260, 260);

    [self.view addSubview:_widController.view];

    //[_widController release];
}

- (void)viewDidUnload {
    [super viewDidUnload];

    self.labelResultString = nil;
}

- (void)dealloc {
    self.labelResultString = nil;
}

- (void)viewWillAppear:(BOOL)animated {
    [super viewWillAppear:animated];

    [_widController viewWillAppear:animated];
}

- (void)viewDidAppear:(BOOL)animated {
    [super viewDidAppear:animated];

    [_widController viewDidAppear:animated];
    [[UIApplication sharedApplication] setStatusBarHidden:NO];
}

- (void)viewWillDisappear:(BOOL)animated {
    [super viewWillDisappear:animated];

    [_widController viewWillDisappear:animated];
}

- (void)viewDidDisappear:(BOOL)animated {
    [super viewDidDisappear:animated];

    [_widController viewDidDisappear:animated];
}

#pragma mark - ZXingDelegateMethods

- (void)zxingController:(ZXingWidgetController*)controller didScanResult:(NSString *)result {
    self.labelResultString.text = result;
}

- (void)zxingControllerDidCancel:(ZXingWidgetController *)controller {
    [self dismissModalViewControllerAnimated:YES];
}

@end

Answer 4

This is a step-by-step tutorial on how to add an integrated QR code reader to your iphone app. Look at this example ZXing project if you need to know how to use it.