You have to have a splash image when your application initialises.
In your case you can definitely go ahead without putting any splash screen into the app, as you are not going through Apple's review. But Apple mandates this for a valid reason. Its all about user experience if not branding. A black screen is like a dingy reception of a hotel which makes the guests dreadful from the very point of arrival.
It is required to use a splash image to get through Apple's review. In case you don't have one which shows your brand name, Apple suggests that you put something very much similar to your app's first screen with no data there.
Design a launch image that is identical to the first screen of the
app, except for:
- Text. The launch image is static, so any text you display in it won’t be localized.
- UI elements that might change. If you include elements that might look different when the app finishes launching, users can experience
an unpleasant flash between the launch image and the first app screen.
If you think that following these guidelines will result in a plain,
boring launch image, you’re right. Remember, the launch image doesn’t
provide you with an opportunity for artistic expression. It’s solely
intended to enhance the user’s perception of your app as quick to
launch and immediately ready for use. For example, Settings and
Weather each supply a launch image that is little more than a static
background image.
Example
If you see Facebook app, they don't show "Facebook" logo as splash screen, but a screen which have a tab bar and navigation bar (actually an image of course). So, it will look to the user that the data is loading.