Undefined symbols for architecture armv7 when using ZXing library in Xcode 4.5
Well, at last I got it working.. For anyone who encounters this in the future..
Rename the main.m file to main.mm.
ZXing's README states why we need this
It can happen that when trying to build your own project with ZXingWidgetController you get linker errors like "undefined reference to". If this error looks like a c++ undefined reference, then renaming main.m into main.mm (Objective-C++ source suffix) may fix the problem
Rename the file (ViewController/View) which uses ZXing librayfunctions so that it also has .mm extension.
Check architecture settings across project. Givearchitecture and valid architecture as armv7 armv7s in your project settings, target settings, and ZXing project (which youadded to your main project) and target settings.
In main project -> Build Settings scroll and find out theoptions, C++ Language Dialect and C++ Standard Library.Select options "Compiler Default" for both of them. (This is thestep I missed, It is needed because newest XCode template hascompiler default settings different to what they were in olderversions).
You also might have to set ZXingWidget's "Build Valid ArchitectureOnly" flag set as
NO. In my case, this field was alreadyNO
These fixed the issue for me..
Update
On December 2013, Google has retired ZXing iOS/Objective C port. So Zxing project for iOS is no longer maintained and updated for new iOS versions. Also Zxing doesn't have support for Arm64 architecture which is one of the standard architecture as per new XCode versions.So developers are encouraged to move over to the native Apple framework to read barcode which is available from iOS7 onwards. See this for a step by step tutorial.
I've followed all of the suggestions above, and while everything compiles fine, the linking fails:
"std::basic_ostream<char, std::char_traits<char> >& std::operator<<<std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)", referenced from: zxing::qrcode::Detector::computeDimension(zxing::Ref<zxing::ResultPoint>, zxing::Ref<zxing::ResultPoint>, zxing::Ref<zxing::ResultPoint>, float) in libZXingWidget.a(Detector-B8B28E953F840D47.o) zxing::GridSampler::checkAndNudgePoints(zxing::Ref<zxing::BitMatrix>, std::vector<float, std::allocator<float> >&) in libZXingWidget.a(GridSampler.o) zxing::qrcode::DecodedBitStreamParser::decodeNumericSegment(zxing::Ref<zxing::BitSource>, std::string&, int) in libZXingWidget.a(DecodedBitStreamParser-64E27B33E79CBC52.o) zxing::qrcode::Mode::forBits(int) in libZXingWidget.a(Mode.o)... "std::ios_base::Init::Init()", referenced from:
___cxx_global_var_init in libZXingWidget.a(QRCodeReader-F470BE6889D3F76D.o) ___cxx_global_var_init in libZXingWidget.a(Decoder-3DF771F40A970F8E.o) ___cxx_global_var_init in libZXingWidget.a(FormatReader.o) ___cxx_global_var_init in libZXingWidget.a(QRCodeReader-C190599C861BFE46.o) ___cxx_global_var_init in libZXingWidget.a(DecodeHints.o) ___cxx_global_var_init in libZXingWidget.a(BinaryBitmap.o) ___cxx_global_var_init in libZXingWidget.a(DecoderResult.o)and so on...
I'm running Xcode 4.5.2. I've renamed main.m to main.mm, my view controller was also renamed from .m to .mm, architecture everywhere is "armv7 armv7s".
Sigh...
Update
Someone on the Apple devforums had the answer to my problem:
It looks like you have mismatched C++ standard libraries. Your project's build settings are using clang's C++ standard library, but libZXingWidget.a was compiled to use the GNU C++ standard library.
Try this: open ZXingWidget.xcodeproj and set the "C++ Standard Library" to "libc++", then Clean everything and rebuild.
If that doesn't work, try setting "C++ Standard Library" to "libstdc++" in both your project and ZXingWidget.xcodeproj
The first suggestion did the trick.
I solved it by changing one value on the project you dragged and dropped in to xcode.
Set:
Build Active Architecture Only -> Debug -> No
Hope that helps people :)!