I integrated passbook with my application. I need some of the pass fields as dynamic. How can I create Pass using dynamic values using passkit framework?
Passkit is the device-side library used to view and manipulate passes. You can't use it to generate passes - this needs to happen outside the device, using your own tools. Apple provide some sample code in Ruby that shows you how to sign and create passes.
I would suggest you take a look at Apple's Pass Design and Creation document, which runs through how to create a pass, sign it, and update it. The updating of passes is what makes a field dynamic.