More or less. The "startup screen" would basically be a screenshot of the "empty" state of the first screen of the app, so, for example, if you had an email app

More or less. The "startup screen" would basically be a screenshot of the "empty" state of the first screen of the app, so, for example, if you had an email app, you'd load a screen which had an empty list where the list of emails would appear and an empty bar at the top where your buttons to compose a new message and such would go, but with the buttons unlabeled - these empty UI elements reduced the odds that your user would try to interact with them yet. Ideally, when the app finished starting up and the screen was replaced with the actual UI with labeled buttons and a populated list, there'd be no visual discrepancy otherwise and it'd look like your app started instantly but then just took a moment to load your emails. This became less practical as the iPhone started getting multiple models with different screen sizes.