1.3. Frequently Asked Questions (FAQ)

This is the ever-growing list of answers to commonly asked questions. Please feel free to post you question in our iPhone Developers forum if you do not find the information you need in this documentation.

1.3.1. General

This looks great... Where can I get it?

You can download the latest version of the SDK from http://zbar.sf.net/iphone

1.3.2. Compatibility

Which iPhone devices does this library support?

The library works only with the iPhone 3GS and iPhone 4.

Will you make it work with the iPhone 3G?

No - the 3G it is not supported and is unlikely to ever be supported.

To be fair, you can use the 3G to scan image files, as long as they’re in focus (ie, not images taken by the built-in fixed-focus camera). There is at least one application that found a use for this...

What target iOS versions does this library work with?

iOS 4 is fully supported, including the latest video streaming interfaces. Since Apple has dropped support for earlier versions of iOS on the App Store, we recommend that you target only iOS 4 for reading barcodes.

iOS 3.1 is also supported, but you will have to resort to manual capture if you intend to distribute on the App Store.

The library should work all the way back to iOS 3.0, although we no longer test with it. For most cases we recommend you use at least iOS 3.1, which introduced several must-have enhancements for the UIImagePickerController (ie, cameraOverlayView and takePicture)

In all cases you will need at least a 4.0 SDK to build.

See Backward Compatibility for details about iOS version fallbacks.

Are any private APIs in use?

No - the binary release of the SDK does not use any private APIs.

OTOH, if you do not care about private APIs (for instance, you are targeting AdHoc or enterprise distribution) and you want to enable automatic capture with iOS 3.1, you can build a version that uses UIGetScreenImage (which is again a private API).

See Backward Compatibility for details.

Does this support “automatic” barcode capture?

Yes - if you use iOS 4, the default configuration will capture barcodes automatically from the video stream.

Again, automatic capture is no longer supported with iOS 3.1 for apps distributed on the App Store.

1.3.3. Building

I get “Undefined symbols” errors when I try to build?

Most likely you did not add all of the necessary framework dependencies. See ZBar SDK Integration Tutorial or Installing the SDK for the list of frameworks you need to link against.

1.3.4. Licensing

Please refer to Licensing the Library for questions about licensing.

1.3.5. Barcodes

Why do my UPC barcodes have an extra 0 at the front?

The UPC-A symbology is the subset of EAN-13 that starts with a leading 0. The ZBar decoder enables only EAN-13 by default, so GTIN-13 product codes are consistently reported. You can choose to receive the 12-digit results instead by explicitly enabling UPC-A.

The type property of the symbol can be used to see which type of barcode is reported.

See EAN-13 and UPC-A for more information.

Why does my UPC-E (short version) barcode data look completely wrong?

UPC-E is a “zero compressed” version of UPC-A; certain of the zeros are removed from the UPC-A data to generate the UPC-E barcode. The ZBar decoder expands this compression by default, again to consistently report GTIN-13 product codes. You can choose to receive the compressed 8-digit results instead by explicitly enabling UPC-E.

The type property of the symbol can be used to see which type of barcode is reported.

See UPC-E for more information.