Can I get GMT offset from a TimeZone object?

I have a routine for converting the Long returned by now() into a local time string. I have hard-coded the offset from GMT, which is 4 hours for me during daylight savings time. I would like to improve my routine so that it works in other places and doesn't need to be modified when we switch to daylight wasting time. I can get a TimeZone object from location.timeZone. I cannot seem to find any documentation that says what fields are within a TimeZone object. I am hoping one of them is an integer with the offset I need.

You want location.timeZone.rawOffset

You will need to do arithmetic on that depending on what your need is. I believe it is expressed in milliseconds.

Thanks. I can do arithmetic.
rawOffset if set to 18 million milliseconds which is 5 hours. I believe that is correct for Eastern Standard Time. Is there a good way to know whether daylight savings time is in place?
On a more general point, where can I get documentation on this type of thing? It doesn't seem like posting here is the most efficient way to find this information.