Decoding hangs or returns nil without an error

[ghost]

I'm testing ZXingObjC to use in a future project on OS X. It will use the library to recognize bar codes in images from a certain directory. To test the library I used some simple barcodes (attached at the bottom).

My test-case is built on a default Xcode 4 Cocoa project. I added an NSImageView (imageView) and a NSTextField (textField) to show the image and results.

I'm using the following code to load and process the image:

- (void)applicationDidFinishLaunching:(NSNotification *)aNotification
{
    // Set load and set image
    NSImage *image = [[[NSImage alloc] initWithContentsOfFile:[@"~/Documents/test.jpg" stringByExpandingTildeInPath]] autorelease];
    imageView.image = image;

    // Clear result text field
    textField.stringValue = @"";

    CGImageRef imageToDecode = [image CGImageForProposedRect:nil context:nil hints:nil];  // Given a CGImage in which we are looking for barcodes

    ZXLuminanceSource* source = [[[ZXCGImageLuminanceSource alloc] initWithCGImage:imageToDecode] autorelease];
    ZXBinaryBitmap* bitmap = [ZXBinaryBitmap binaryBitmapWithBinarizer:[ZXHybridBinarizer binarizerWithSource:source]];

    NSError* error = nil;

    // There are a number of hints we can give to the reader, including
    // possible formats, allowed lengths, and the string encoding.
    ZXDecodeHints* hints = [ZXDecodeHints hints];

    ZXMultiFormatReader* reader = [ZXMultiFormatReader reader];
    ZXResult* result = [reader decode:bitmap
                                hints:hints
                                error:&error];
    if (result) {
        // The coded result as a string. The raw data can be accessed with
        // result.rawBytes and result.length.
        NSString* contents = result.text;

        // The barcode format, such as a QR code or UPC-A
        ZXBarcodeFormat format = result.barcodeFormat;
        [hints addPossibleFormat:kBarcodeFormatCode128]; // ##############

        textField.stringValue = [NSString stringWithFormat:@"%@ (%u)", contents, format];
    } else {
        // Use error to determine why we didn't get a result, such as a barcode
        // not being found, an invalid checksum, or a format inconsistency.
        textField.stringValue = @"Error";
    }
}

It is - as you probably recognized - 99% example code from the README. I also added al the frameworks from the OSX section of the README. The app builds, but then it goes wrong. At first it just hanged while taking 100% CPU. I actually did let it run for an hour or so, guess it's safe to say that it isn't doing some real processing.

After trying several things, I discovered that it didn't hung when adding some possible formats. I tried a few and the results were strange to me:

• kBarcodeFormatEan8 recognizes everything as "00000000"
• kBarcodeFormatCode128 doesn't recognize anything at all
• kBarcodeFormatCode39 hangs

I don't think I misconfigured it, I tried a lot of different images and formats, but the results is the same.

I'm running OS X 10.8.4 with Xcode 4.6.2.

[cwalcott]

Just confirmed that these issues are fixed as of 2.2.0