Identifying application uniquely and include a check in a file shared by more than one application-Collection of common programming errors

I have two iPad applications and there is one common project used my both these applications. In order to implement a particular task for UI, I need to deal with a file in the Common project that is being shared. But,when I am working with this file which is there in that project shared by my both applications, I have to check what application is running and make changes appropriately. In case first application is currently running, then I should execute a function and in case if second application is running, I should not execute this function. Is there any way to check which application is running ?