Hi @Mehedi_Hasan2, welcome to the forums.

With the same configuration you have, the apps I build and run work correctly both on the simulator as well as the physical device. More than likely this means there’s a configuration or environment issue. Possibly the Package version or perhaps the Podfile is not set up correctly.

We would need more information to propose a solution.

I would suggest creating a brand new project, install and set up Realm per the Install Guide and try it again.

Report back your finding and include more information about how Realm is added, versions etc.