iPhone: NSDate convert GMT to local time

NSDate *sourceDate = [NSDate dateWithTimeIntervalSince1970:gmtTimestamp];
NSTimeZone* destinationTimeZone = [NSTimeZone systemTimeZone];
NSInteger sourceGMTOffset = [destinationTimeZone secondsFromGMTForDate:0];
NSInteger destinationGMTOffset = [destinationTimeZone secondsFromGMTForDate:sourceDate];
NSTimeInterval interval = destinationGMTOffset - sourceGMTOffset;
NSDate* destinationDate = [[[NSDate alloc] initWithTimeInterval:interval sinceDate:sourceDate] autorelease];
NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
dateFormatter.dateFormat = @"yyyy-MM-dd'T'HH:mm";
[dateFormatter setTimeZone:destinationTimeZone];
NSString *localTimeString = [dateFormatter stringFromDate:destinationDate];

This code will convert the GMT time to the device's local time.

NSDate* localDateTime = [NSDate dateWithTimeInterval:[[NSTimeZone systemTimeZone] secondsFromGMT] sinceDate:pubDate];

NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
dateFormatter.dateFormat = @"yyyy-MM-dd'T'HH:mm";

NSTimeZone *gmt = [NSTimeZone timeZoneWithAbbreviation:@"GMT"];
[dateFormatter setTimeZone:gmt];
NSString *timeStamp = [dateFormatter stringFromDate:[NSDate date]];
[dateFormatter release];