OCR for Imported Documents
At the time of your initial posted question in April 2013, the only way to OCR PDF files with iOS apps was to take screen captures of the images and run an OCR of the individual images from the camera roll. The alternative was to upload the PDFs to a conversion server, either via apps that could run the OCR fairly fast at a charge per page or where you'd have to wait for the results to come back. However, with the release of the version 2 upgrade to the Prizmo app on May 14, 2013, you can run OCRs directly from PDFs, have support for multipage documents, and also have Dropbox integration. Alternatively, if you received the multi-page PDF document as an attachment in mail, you can double tap on the attachment, and then "open in" Prizmo. The work flow has been considerably simplified with a "Recognize" button, and you can also export as text, PDF, or searchable PDF to other apps, including Dropbox.