GMT로 시간데이터를 받아올 경우, 시차 적용법

NSDate *currentRealDate = [NSDate date];

NSTimeZone *timeZone = [NSTimeZone defaultTimeZone];

NSDateComponents *offsetComponents = [[NSDateComponents alloc] init];

[offsetComponents setSecond:(-1*[timeZone secondsFromGMTForDate:currentRealDate])];

NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];

NSDate *currentDate = [gregorian dateByAddingComponents:offsetComponents toDate:currentRealDate options:0];