ios - Get current iPhone device timezone date and time from UTC-5 timezone date and time iPhone app?

Question

In my iPhone application i am very struggling to convert the webservice response time to current device time. The webservice time in UTC-5 timezone. The app is worldwide use app. So i have to convert the response time to current device timezone. This is simple messaging app.

When i have sent a message the time is "5:05 PM" (India Chennai timezone) but when am retrieve time from webservice is "2012-07-16 07:33:01". When i show the time in the app i should convert the time to device's local time. I have tried in some way but i can't solve yet. Code is:

NSDateFormatter *dateFormatter1 = [[NSDateFormatter alloc] init]; 
[dateFormatter1 setDateFormat:@"yyyy-MM-dd HH:mm:ss"]; 
[dateFormatter1 setLocale:[NSLocale currentLocale]];
//[dateFormatter1 setTimeZone:[NSTimeZone timeZoneWithName:@"IST"]];
[dateFormatters setTimeZone:[NSTimeZone systemTimeZone]];
NSDate *date = [dateFormatter1 dateFromString:dateStr];
NSLog(@"date : %@",date);

But the output date and time is 2012-07-16 02:03:01 +0000 I have stored this date/time in Coredata and when I have retrieve from CoreData and covert to NSString using the below code,

NSDateFormatter *dateFormatters = [[NSDateFormatter alloc] init];
[dateFormatters setDateFormat:@"dd-MMM-yyyy hh:mm"];
[dateFormatters setDateStyle:NSDateFormatterShortStyle];
[dateFormatters setTimeStyle:NSDateFormatterShortStyle];
[dateFormatters setDoesRelativeDateFormatting:YES];
[dateFormatters setTimeZone:[NSTimeZone systemTimeZone]];  
dateStr = [dateFormatters stringFromDate:dateString];
NSLog(@"DateString : %@", dateStr);

The output date and time is "Today 7:33 AM". It should be show "Today 5:05 PM". Can anyone please save my day? Please help to solve this issue. Thanks in advance.

Answer 1

I have tested your scenario and added some code for your reference. Please test the below and please let me know it is useful for you.

NSString *dateStr = @"2012-07-16 07:33:01";
NSDateFormatter *dateFormatter1 = [[NSDateFormatter alloc] init]; 
[dateFormatter1 setDateFormat:@"yyyy-MM-dd HH:mm:ss"]; 
NSDate *date = [dateFormatter1 dateFromString:dateStr];
NSLog(@"date : %@",date);

NSTimeZone *currentTimeZone = [NSTimeZone localTimeZone];
NSTimeZone *utcTimeZone = [NSTimeZone timeZoneWithAbbreviation:@"UTC"];

NSInteger currentGMTOffset = [currentTimeZone secondsFromGMTForDate:date];
NSInteger gmtOffset = [utcTimeZone secondsFromGMTForDate:date];
NSTimeInterval gmtInterval = currentGMTOffset - gmtOffset;

NSDate *destinationDate = [[[NSDate alloc] initWithTimeInterval:gmtInterval sinceDate:date] autorelease];

NSDateFormatter *dateFormatters = [[NSDateFormatter alloc] init];
[dateFormatters setDateFormat:@"dd-MMM-yyyy hh:mm"];
[dateFormatters setDateStyle:NSDateFormatterShortStyle];
[dateFormatters setTimeStyle:NSDateFormatterShortStyle];
[dateFormatters setDoesRelativeDateFormatting:YES];
[dateFormatters setTimeZone:[NSTimeZone systemTimeZone]]; ?
dateStr = [dateFormatters stringFromDate: destinationDate];
NSLog(@"DateString : %@", dateStr);

Thanks.