Howdy!
How would I show a spinning UIActivityIndicatorView on app launch (in center of view/ not on status bar), to show a background busy activity like restore purchases, or connecting to our authentication servers? We are using a storyboard as our launch image.
You can create your own UIView with a spinner inside it. You show it onscreen when you call the authentication method and hide it when the callback returns finished.
You can also find many such github projects by googling for them, here is one: