If my iPhone app needs to update the Core Data database, I would like to show an MBProgressHUD view to users while my iPhone app is loading, so they know that it's working and not hanging. How might I go about adding an MBProgressHUD to the splash screen while the data store is migrating? Normally I would attach it to the UIViewController's view, but the splash screen is under the app delegate. Is this possible to do?
No it is not possible to overlay anything over the splash screen as it's static.
You could, however, delay the intensive process for a bit until the app loads, then create a fake splash screen with the progress indicator while the intensive stuff goes on in a background thread.