How can I simply scan barcodes on iPhone and/or iPad?
We produced the 'Barcodes' application for the iPhone. It can decode QR Codes. The source code is available from the zxing project; specifically, you want to take a look at the iPhone client and the partial C++ port of the core library. The port is a little old, from circa the 0.9 release of the Java code, but should still work reasonably well.
If you need to scan other formats, like 1D formats, you could continue the port of the Java code within this project to C++.
EDIT: Barcodes and the iphone
code in the project were retired around the start of 2014.
Sean what kind of licence does it use. I want to create a payed app that uses Zbar. Is that possible under the licence agreement ?
Just to be clear, at this point in time, ZXing on the iPhone only supports QR Codes?
I believe more has been ported to C++, but the port is still a rough and outdated echo of the Java code unfortunately. So, yes more is supported though perhaps not well.
ZXing for iPhone has still memory leaks by 1.7 ver.
I understand from the issue list on git of zXing that we can scan barcode only in landscape mode.