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Undefined symbols for architecture armv7 when using ZXing library in Xcode 4.5

Asked 2012-10-19T06:15:00.650
37

What I am trying to do

Integrate Zxing, QR code reader framework, in my iPhone project. I checked out ZXing sdk from here. I ran the sample project coming with ZXing, named ScanTest, without any issues. But when I try to integrate the library with my project I am getting the error mentioned.

Project specification

  • Target OS : iOS 6.0
  • Deployment target : iOS 5.0 or above.
  • Tested on : iPhone 4 and iPhone 3GS.
  • Xcode : Xcode 4.5.1
  • ZXing version : 2.0

Problem

When I build, after doing every integration step in ZXing readme file, I am getting build errors like

Undefined symbols for architecture armv7:
  "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)

Undefined symbols for architecture armv7:
"std::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string(char const*, std::allocator<char> const&)", referenced from:
      zxing::Exception::Exception(char const*) in libZXingWidget.a(Exception.o)
      zxing::common::StringUtils::guessEncoding(unsigned char*, int, std::map<unsigned int, std::string, std::less<unsigned int>, std::allocator<std::pair<unsigned int const,
ios cocoa-touch ios6 zxing undefined-symbol
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1 Answer

57

Well, at last I got it working.. For anyone who encounters this in the future..

  1. 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

  2. Rename the file (ViewController/View) which uses ZXing libray functions so that it also has .mm extension.

  3. Check architecture settings across project. Give architecture and valid architecture as armv7 armv7s in your project settings, target settings, and ZXing project (which you added to your main project) and target settings.

  4. In main project -> Build Settings scroll and find out the options, C++ Language Dialect and C++ Standard Library. Select options "Compiler Default" for both of them. (This is the step I missed, It is needed because newest XCode template has compiler default settings different to what they were in older versions).

  5. You also might have to set ZXingWidget's "Build Valid Architecture Only" flag set as NO. In my case, this field was already NO

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 en

answered 2012-10-19T08:20:24.007

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