Time difference between two different times.

NSDateFormatter* dateFormatter = [[[NSDateFormatter alloc] init] autorelease];

[dateFormatter setLocale:[[[NSLocale alloc] initWithLocaleIdentifier:@"en_US_POSIX"] autorelease]];

[dateFormatter setDateFormat:@"hh:mm:ss"];

NSDate* firstDate = [dateFormatter dateFromString:starttime];

NSDate* secondDate = [dateFormatter dateFromString:endtime];

NSTimeInterval ti = [secondDate timeIntervalSinceDate:firstDate];

//NSString *str1 = [NSString stringWithFormat:@"%d",ti];

//NSLog(@"str1 %@",str1);

NSUInteger h, m, s;

h = (ti / 3600);

m = ((NSUInteger)(ti / 60)) % 60;

s = ((NSUInteger) ti) % 60;

NSString *str = [NSString stringWithFormat:@"%d:%02d:%02d", h, m, s];

//NSLog(@" strdiff : %@ ",str);