HWR/OCR
As for me, best of OCR engines is Tesseract; it recognizes text better then even ABBYY.
http://stackoverflow.com/questions/1739109/chinese-handwriting-recognition
Chinese handwriting recognition
http://stackoverflow.com/questions/1722269/mobile-ocr-engine-for-iphone-app/15950144#15950144
Mobile OCR Engine for iPhone app
http://blog.csdn.net/gqqnb/article/details/6572986
https://github.com/touchaddict/Lipi-ToolKit
Lipi-ToolKit（Linux版，可以开发，用于识别）
http://tomoe.sourceforge.jp/cgi-bin/en/blog/index.rb
Tomoe - A handwriting recognition engine
http://tegaki.org/ tegaki project
Mobile OCR Engine for iPhone app
http://stackoverflow.com/questions/1722269/mobile-ocr-engine-for-iphone-app/15950144#15950144
There are many libraries available for extracting text from images.
Tesseract and Abby are the best OCR SDK's I have used. The main advantage with Abby SDK is that its results are nice as compare to Tesseract . And the only disadvantage with it is that it is purchasable . While the main advantage in Tesseract is that it is open source and you can improve its result by using any image processing library.
1) Abby - https://github.com/abbyysdk/ocrsdk.com it uploads the image to its server, converts image to text and downloads the result
2) Tesseract - https://github.com/nolanbrown/Tesseract-iPhone-Demo/tree/master/OCRDemo It converts the image to text using tessrect sdk. Not as accurate result as Abby but does not require internet connection.
3) Tesseract + OpenCV - https://github.com/pablosproject/iPhone-OCR-Tesseract-and-OpenCVProbably the best sdk I found so far to read image without internet connection. Advantage of this code is it integrates OpenCV too, thus you can add algorithms like blog extraction algorithm and hough transform to increase the accuracy of result.
I hope it helps.
http://stackoverflow.com/questions/9108507/how-to-implement-handwriting-recognition-in-ipad
There are no "text" gesture recognizers. What you are describing is called handwriting recognition.
The only built-in support for handwriting recognition is in the Chinese "keyboard" settings labeled "handwriting". There is no API for handwriting recognition.
There do not appear to be any open-source handwriting recognition projects specifically for iOS.
You should just look for a generic open-source handwriting recognition library and port it to iOS.