如何检查从哪个viewcontroller导航...在obj c

I am in a context where From some 3 classes I am navigating to a class say classX, and I have a back button on classX, on click of that back button I need to navigate to the class from which it has been navigated, so I need to check from which viewcontroller its been navigated, is it possible to do with out using I am in a context where From some 3 classes I a