It does not mean a subclass that derives from the SplashScreen class. The phrase "extended splash screen" in this topic refers to a splash screen that stays on the screen for an extended period of time. Whether you want to show real-time loading information or simply give your app extra time to prepare its initial UI, an extended splash screen lets you define the launch experience. This extended screen imitates the splash screen shown when your app is launched, but can be customized.
Display a splash screen for more time by creating an extended splash screen for your app.