nsdate - objective-c: Conversion between TimeZones -

i'm having problems converting time string different timezone.

this string example 1 retrieve server: @"5/14/2013 4:19am"

i know timezone america/new_york , want convert local timezone: europe/rome.

here code wrote test it:

-(void) converttimezone {         nsdateformatter *dateformatter = [[nsdateformatter alloc] init];     dateformatter.timezone=[nstimezone timezonewithabbreviation:@"gmt"];     dateformatter.dateformat=@"mm/dd/yyyy hh:mma";     nsstring *sourcedatestring = @"5/14/2013 4:19am";      nstimezone *sourcetimezone = [[nstimezone alloc] initwithname:@"america/new_york"];     nstimezone *destinationtimezone = [nstimezone localtimezone];     nsinteger sourcegmtoffset = sourcetimezone.secondsfromgmt;     nsinteger destinationgmtoffset = destinationtimezone.secondsfromgmt;     nsinteger interval = destinationgmtoffset-sourcegmtoffset;       nslog(@"dateformatter timezone: %@", dateformatter.timezone);     nslog(@"source timezone: %@", sourcetimezone);     nslog(@"destination timezone: %@", destinationtimezone);     nslog(@"sourceoffset: %u destinationoffset: %u interval: %u", sourcegmtoffset, destinationgmtoffset, interval);      nslog(@"----------------------------------------------------------------------------------------------------");      nslog(@"sourcedatestring : %@", sourcedatestring);      //convert string date      nsdate *dateobject = [dateformatter datefromstring:sourcedatestring];     nslog(@"from string date: %@", dateobject);      //now date string     nslog(@"from date string: %@", [dateformatter stringfromdate:dateobject]);      //convert sourcetimezone destinationtimezone     nsdate *newdate = [[nsdate alloc] initwithtimeinterval: interval sincedate:dateobject];          nslog(@"destinationdatestring: %@", [dateformatter stringfromdate: newdate]);  } 

output:

---

dateformatter timezone: gmt (gmt) offset 0

source timezone: america/new_york (gmt-04:00) offset -14400 (daylight)

destination timezone: local time zone (europe/rome (cest) offset 7200 (daylight))

sourceoffset: 4294952896 destinationoffset: 7200 interval: 21600

sourcedatestring : 5/14/2013 4:19am

from string date: 2013-05-14 00:19:00 +0000

from date string: 05/14/2013 00:19am

destinationdatestring: 05/14/2013 06:19am

---

i'm getting mad!!!!

if original date "5/14/2013 4:19am" why date formatter changes "05/14/2013 00:19am" ????????? if had saved correctly "05/14/2013 04:19am +0000" conversion perfect (6 hours between 2 timezones)!!!

any hint?

thanks

nicola

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edit

by setting these parameters suggested lithu-t-v:

dateformatter.timezone=[nstimezone timezonewithabbreviation:@"gmt"];  nsstring *sourcedatestring = @"5/14/2013 4:19am -0400"; 

it seems work doesn't.

i "it seems" because:

sourcedatestring: 5/14/2013 04:19am -0400

from string date: 2013-05-13 04:19:00 +0000 (ok)

from date string: 05/14/2013 04:19 (ok)

destinationdatestring: 05/14/2013 10:19 (correct)

is correct if try late pm hour:

sourcedatestring: 5/14/2013 10:19pm -0400

from string date: 2013-05-14 16:19:00 +0000 (wrong)

from date string: 05/14/2013 16:19

destinationdatestring: 05/14/2013 22:19 (wrong!)

the correct result should be: 05/15/2013 04:19am

the +0000 component defines date time zone , provide actual time .a nsdate object include part also.since part missing time difference comes,with respect local time zone

here ceated timezone not set datefromatter.set timezone dateformatter , try it

append +0000 string , remaining.it work