BulldogLowell:
it is quite trivial... it is the difference between UTC and local time.
That assumes you have the UTC and local time. But if trying to actually calculate the local time, getting the correct offset is definitely not trivial when dealing with daylight savings time adjustments.
i.e. if the device has GPS coordinates and UTC, trying to turn that into a local time for that location is not trivial since the local community gets to determine if/how/when any daylight savings/summer time adjustment is done.
The API can furnish both your local time based on the data in your call (city/zip) and UTC.
If that is the case great, but they must have some sort of crazy database that can map GPS coordinates (or cities) to get the appropriate DST rules to take that into account.
getting time zone affinities from municipalities seems sort-of mundane, particularly since generally States 1) pick one and 2) stay in it!
While that is generally true in the USA, it isn't always the case.
And around the World things can be quite different.
And that is the point I'm making. If the API can provide an accurate local time, it must be able to take into consideration all the messy details of daylight savings time in various locations.
--- bill