Unable to get correct time with time interval from epoch in iOS

Question

This is my time value in milliseconds

UInt64 time = 1490237914000;

I use the following method to get the correct time representation

- (NSString *)commonRepresentationForTimerValue:(UInt64)timerValue
{
    NSDate *date = [NSDate dateWithTimeIntervalSince1970:timerValue];
    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSDateComponents *components = [calendar components:(NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitWeekday) fromDate:date];

    NSInteger hour = [components hour];
    NSInteger minute = [components minute];
    NSInteger weekDay = [components weekday];

    NSString *hourString;

    if(hour < 10)
    {
        hourString = [NSString stringWithFormat:@"%@%li", @"0", (long)hour];
    }

    else
    {
        hourString = [@(hour) stringValue];
    }

    NSString *minuteString;

    if(minute < 10)
    {
        minuteString = [NSString stringWithFormat:@"%@%li", @"0", (long)minute];
    }

    else
    {
        minuteString = [@(minute) stringValue];
    }

    NSString *weekDayString;

    switch(weekDay)
    {
        case 1: weekDayString = @"Sunday"; break;
        case 2: weekDayString = @"Monday"; break;
        case 3: weekDayString = @"Tuesday"; break;
        case 4: weekDayString = @"Wednesday"; break;
        case 5: weekDayString = @"Thursday"; break;
        case 6: weekDayString = @"Friday"; break;
        case 7: weekDayString = @"Saturday"; break;
    }

    NSString *timerString = [NSString stringWithFormat:@"%@:%@ %@", hourString, minuteString, weekDayString];

    return timerString;
}

This is what I am getting from the above code:

2017-03-23 12:20:02.318 AutoLayoutTest[21746:3371016] Time is 08:06 Tuesday

That output is incorrect (I know it's incorrect).

I tested the same value with Java

public static void main(String[] args) 
    {
        Long timer = 1490237914000l;

        final Calendar calendar = Calendar.getInstance();
        DateFormat formatter = new SimpleDateFormat("hh:mm");
        calendar.setTimeInMillis(timer);

        String weekDay = null;

        switch (calendar.get(Calendar.DAY_OF_WEEK)) 
        {
            case 0: weekDay = "Sunday"; break;
            case 1: weekDay = "Monday"; break;
            case 2: weekDay = "Tuesday"; break;
            case 3: weekDay = "Wednesday"; break;
            case 4: weekDay = "Thursday"; break;
            case 5: weekDay = "Friday"; break;
            case 6: weekDay = "Saturday"; break;
        }

        System.out.println("Time is " + formatter.format(calendar.getTime()) + " " +  weekDay);
    }

I got the correct output

Time is 10:58 Friday

I tried to change this line of code

NSDate *date = [NSDate dateWithTimeIntervalSince1970:timerValue];

to the following:

NSDate *date = [NSDate dateWithTimeIntervalSinceNow:timerValue];

and

NSDate *date = [NSDate dateWithTimeIntervalSinceReferenceDate:timerValue];

I still get incorrect result.

I don't know where the problem is, because the time value is the time from epoch, and in java it works. There must be something I am misunderstanding here but I am unable to determine it.

Answer 1

I solved the problem myself. I just divided the value of the timer by 1000.

NSDate *date = [NSDate dateWithTimeIntervalSince1970:timerValue/1000];

and that solves the problem.