The available OCR plug-in can recognize text which you can edit, copy and search from scanned PDF. With PDF Editor Pro for Mac, you can edit scanned PDF documents directly such as add annotation, mark up with drawing, add text and images, etc.

Video Demo:
Code:
youtube.com/watch?v=FxwV-AIPjYw
This video tutorial covers:
1. Perform OCR on scanned PDF

2. Modify/Add Text in scanned PDF
3. Annotate scanned PDF