A Boolean value that indicates whether TCP connections should be kept open when the app moves to the background.
- iOS 9.0+
- macOS 10.11+
- Mac Catalyst 13.0+
- tvOS 9.0+
- watchOS 2.0+
In addition to requesting that the connection be kept open, setting this value to
true asks the system to delay reclaiming the connection when the app moves to the background.