iOS View controller memory management

Memory management key:

viewDidUnload is only called if there is a low memory situation and your view is not the active view.

otherwise just calls dealloc.

For all view controllers simulate memory warning to test their handling

viewDidLoad v viewWillAppear: viewWillAppear is called multiple times, everytime the view comes back into view. For example

when a modal view is quit revealing the original view again.