OpenCV 2.4.4 and Tesseract 3.02.02 Don't link together

Question

I'm using iOS 6.1 and XCode 4.6

I have a problem, OpenCV needs to be compiled with libc++ (LLVM C++ 11), while Tesseract 3.02.03 needs to be compiled with "default compiler".

How can I overcome this problem. at this point I can compile and link only If I comment out OpenCV code or comment out OCR code. cannot make them both work together.

Any ideas??

Answer 1

I am by no means an expert with C++ but I had the same problem and by some trial and error and lots of internet searching I think I managed to solve it.

As I understand it, the problem is that opencv and tesseract are built with different standard libraries. The latest opencv is built with libc++ while tesseract is built with stdlibc++

The solution is to rebuild one of them so they both use the same standard library. I decided to recompile tesseract and followed the instructions found here which references a build script that is used to build the library.

I modified this script (again, by trial an error, not really sure this is the best way) to used the clang++ compiler (CXX="/usr/bin/clang++") and use libc++ (CXXFLAGS="$CFLAGS -stdlib=libc++") and it compiles (albiet with some warnings). You may also need to copy some headers as the script doesn't seem to copy them all.

Then just use this library instead of the downloaded one in your iOS project (remember to change back to libc++ in build settings) and everything will compile and link just fine.

So far it seems to work properly in runtime.