Trying to find a way to allow users to download apps for free with the developers permission. (Like a free app a day) but not having the app store pricing change. Is there a way to use the skstoreproductviewcontroller in order to allow users to download an app as a promotion for free without making that app free on the app store itself?
No this is not possible. In order to make the app free, you would have to make it free everywhere (in the App Store and in the SKStoreProductViewController as well).