An Objective-C message was sent to a deallocated object (zombie) at address: 0x75d52a0
I feel you are not using ARC, and you are not retaining of passing your previous object. In the meantime the previous object is released and then you accessing it.
Either you can refactor your code to use ARC or put retain or autorelease.
Go to Product > edit scheme >Diagnostics tap then check on enable Zombie objects
make a break point and go step by step to know which object is deallocated, it perhaps the pointer to your object has been removed then the OS has deallocated your object.