Returns the difference in seconds between the receiver and Greenwich Mean Time at a given date.
- iOS 2.0+
- macOS 10.0+
- Mac Catalyst 13.0+
- tvOS 9.0+
- watchOS 2.0+
The date against which to test the receiver.
The difference in seconds between the receiver and Greenwich Mean Time at
The difference may be different from the current difference if the time zone changes its offset from GMT at different points in the year—for example, the U.S. time zones change with daylight saving time.