Speed difference HFS and NTFS for data

Question

I need to get date for the first day of the week from any date. This code works fine, but for some dates I get a very strange result. A date from the first week of the year converts to last week's date:

NSTimeInterval ti = 1420311299;
NSDate* date = [NSDate dateWithTimeIntervalSince1970:ti];

NSLog(@"%@", date); // OUTPUT: 2015-01-03 18:54:59 +0000

NSCalendar* calendar = [NSCalendar currentCalendar];
NSDateComponents *cmps = [calendar components:(kCFCalendarUnitWeekOfYear | kCFCalendarUnitYear) fromDate:date];

cmps.weekday = calendar.firstWeekday;

NSLog(@"%@", cmps); // OUTPUT:  Calendar Year: 2015
                    //          Week of Year: 1
                    //          Weekday: 1



NSDate* newDate = [calendar dateFromComponents:cmps];

NSLog(@"%@", newDate); // OUTPUT: 2015-12-26 22:00:00 +0000

Solution

It does not really matter. See here for more on the subject (though not a lot more).

Comments

[soandos]

Remove the second to last line unless you want the question to get closed.

[oxigen]

Thanks. I'll try it. About 2-nd part. As you can see in my example, 3rd of January is a part of 53 week of CURRENT 2015 year. And I can't understand, how is it possible...

[vikingosegundo]

It sounds strange, but this is expected behavior. Even Apple steps into this issue twice: alarms not going off the first few days of a year.