can I use dynamic library(shared object) in my iphone app?

As Bernardo Ramos states in a comment: "Since iOS8 we can use dynamic libraries".

Dynamic libraries are not allowed by the App Store. No code may be loaded at run-time. The answer is to convert them to static libraries and compile them into the application.

From iPhoneOSTechOverview:

"If you want to integrate code from a framework or dynamic library into your application, you should link that code statically into your application’s executable file when building your project."

Read "should" as "must"

See SO Answer: Can create dynamic library for iOS?