问题:

I want to develop an iPhone application that is going to convert some sort of images to text formats. I want to know that is there any built-in library for achieving this purpose?

回答1:

I suppose you are asking about recognizing text from images (OCR) and not about something like encoding image file into base64

There's no build-in OCR libraries in iPhone.

Depending on your budget and what accuracy you trying to achieve, you can try

Commertical OCR - MSDK from ABBYY http://abbyy.com/mobileocr/iphone - high accuracy, customer support, etc. but costs money. Disclaimer: I work for ABBYY
Open Source OCR - Tesseract http://code.google.com/p/tesseract-ocr/ - completely free, but less accurate. This sample shows how to run it on iPhone: https://github.com/nolanbrown/Tesseract-iPhone-Demo

回答2:

I have used tesseract. Its accuracy ranges from 0-100% depending upon various factors like how well the image is captured,fonts and color of the text etc.

But it can give you very good result if you have a very clear image with very clear text.