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+
Tsseract-OCR-iOS has been updated to handle this issue (working in the same project as a libc++ compiled project e.g. OpenCV). Don't forget these steps when installing it:
If you are using iOS7 or greater, link libstdc++.6.0.9.dylib library (Your target => General => Linked Frameworks and Libraries => + => libstdc++.6.0.9)
Go to your project, click on the project and in the Build Settings tab add -lstdc++ to all the "Other Linker Flags" keys.
*Go to your project settings, and ensure that C++ Standard Library => Compiler Default. (thanks to https://github.com/trein)
Copy and import the tessdata folder from the Template Framework Project under the root of your project. It contains the "tessdata" files. You can add more tessdata files copyng them here.
*I had to set the C++ Standard Library to "libc++" in order for OpenCV to compile.