Q:

Loading a UIViewController from the stack

I am new to iPhone app development.  I'm very confused with the concepts of views and view controllers.  
My question is as follows:
I have a UIViewController.  For the purposes of the example, let's call this one A.
From this I load another view controller B using presentModalViewController.  
On the presentModalViewcontroller I push yet another view controller C. From this view controller I want to load the first mentioned view controller A. I read that these views are arranged in stacks.  However I am not sure about how to do it.  
How can I load the same view controller A in this case? 

A:

Use the -[UIViewController presentingViewController] method on C:
UIViewController *A = C.presentingViewController;

This will return the view controller that sent presentModalViewController:animated:.  If you want to provide information back to A, I'd go for delegation instead but the above works too. 

If your question was how to get back to A (i.e. dismiss the modal view controller), use this:
UIViewController *A = C.presentingViewController;
[A dismissModalViewControllerAnimated:YES];

