title: how to check from which viewcontroller it has been navigated ....in obj c
body: <p>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 <strong><code>UINavigationController</code></strong> ?</p>