iphone how to get timezone? - iphone

Question

i want to get timezone but cant.
i use NSLog is show to me is show.time = 2011-06-29 04:20:00 +0000
here is my code.
-(IBAction)Save:(id)sender{
NSCalendar *calendar = [NSCalendar autoupdatingCurrentCalendar];
//[calendar setTimeZone:[NSTimeZone timeZoneWithName:#"GMT"]];
// Get the current date
NSDate *pickerDate = [self.datePicker date];
// Break the date up into components
NSDateComponents *dateComponents = [calendar components:( NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit )
fromDate:pickerDate];
NSDateComponents *timeComponents = [calendar components:( NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit )
fromDate:pickerDate];
// Set up the fire time
NSDateComponents *dateComps = [[NSDateComponents alloc] init];
[dateComps setDay:[dateComponents day]];
[dateComps setMonth:[dateComponents month]];
[dateComps setYear:[dateComponents year]];
[dateComps setHour:[timeComponents hour]];
// Notification will fire in one minute
[dateComps setMinute:[timeComponents minute]];
[dateComps setTimeZone:[NSTimeZone timeZoneWithAbbreviation:#"GMT"]];
//[dateComps setSecond:[timeComponents second]];
timedata = [calendar dateFromComponents:dateComps];
[dateComps release];
DataClass *obj=[DataClass getInstance];
obj.showdate = timedata;
//NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];
//[defaults setObject:timedata forKey:#"selectdate"];
//NSLog(#"save time = %#",obj.showdate);
[self dismissModalViewControllerAnimated:YES];
}

Answer 1

You're setting the time zone for your NSDateComponents object to GMT:
[dateComps setTimeZone:[NSTimeZone timeZoneWithAbbreviation:#"GMT"]];
Thus your date will be interpreted as being in GMT. If you want the time zone that the device is in, use systemTimeZone:
[dateComps setTimeZone:[NSTimeZone systemTimeZone]];
In general, as noted in the docs for timeZoneWithAbbreviation:, the abbreviations can be ambiguous. If you want to get a particular time zone in a way that will always work no matter the location of the device, you can use timeZoneForSecondsFromGMT:.
You can also set a time zone for your app, if you want, rather than always referring to a specific time zone when creating date-related objects:
[NSTimeZone setDefaultTimeZone:[NSTimeZone timeZoneForSecondsFromGMT:60*8]];
NSTimeZone * appTZ = [NSTimeZone defaultTimeZone];