iPhone:Find the current timezone offset in HOURS

There is a very nice NSTimeZone object which will give you the timezone offset from GMT in seconds:

float timezoneoffset = ([[NSTimeZone systemTimeZone] secondsFromGMT] / 3600.0);

For more see blog post

http://blog.indieiphonedev.com/2011/01/09/getting-the-timezone-on-the-device/