The amount of time the app has to run in the background.
- iOS 4.0+
- tvOS 9.0+
This property contains the amount of time the app has to run in the background before it may be forcibly killed by the system. While the app is running in the foreground, the value in this property remains suitably large. If the app starts one or more long-running tasks using the
begin method and then transitions to the background, the value of this property is adjusted to reflect the amount of time the app has left to run.