Xcode 4.6, iOS SDK 6.1, tesseract-ocr 3.02
Since the last OpenCV versions are built using libc++, and tesseract-ocr is built using libstdc+
Ok, so my problem was that after adding and removing references to libraries a few times in my project, I had quite a mess in my Library Search Paths. Plus, I didn't add the new "include" folder (created when building tesseract) to the User Header Search Paths.
So, just a quick recap, in order to build tesseract-ocr using libc++, so it can work along with newer OpenCV versions:
That's it. At this point, you'll have a project capable of using both new OpenCV versions AND tesseract 3.02 together. If it's a new project, don't forget to edit your prefix file accordingly to include OpenCV and Tesseract in case of __cplusplus, and rename any .m file using them to .mm
Big thanks to to this answer, that got me well on my way.