How do I break down an NSTimeInterval into year, m

Question

I have a time interval that spans years and I want all the time components from year down to seconds.

My first thought is to integer divide the time interval by seconds in a year, subtract that from a running total of seconds, divide that by seconds in a month, subtract that from the running total and so on.

That just seems convoluted and I've read that whenever you are doing something that looks convoluted, there is probably a built-in method.

Is there?

I integrated Alex's 2nd method into my code.

It's in a method called by a UIDatePicker in my interface.

NSDate *now = [NSDate date];
NSDate *then = self.datePicker.date;
NSTimeInterval howLong = [now timeIntervalSinceDate:then];

NSDate *date = [NSDate dateWithTimeIntervalSince1970:howLong];
NSString *dateStr = [date description];
const char *dateStrPtr = [dateStr UTF8String];
int year, month, day, hour, minute, sec;

sscanf(dateStrPtr, "%d-%d-%d %d:%d:%d", &year, &month, &day, &hour, &minute, &sec);
year -= 1970;

NSLog(@"%d years\n%d months\n%d days\n%d hours\n%d minutes\n%d seconds", year, month, day, hour, minute, sec);

When I set the date picker to a date 1 year and 1 day in the past, I get:

1 years 1 months 1 days 16 hours 0 minutes 20 seconds

which is 1 month and 16 hours off. If I set the date picker to 1 day in the past, I am off by the same amount.

Update: I have an app that calculates your age in years, given your birthday (set from a UIDatePicker), yet it was often off. This proves there was an inaccuracy, but I can't figure out where it comes from, can you?

Answer 1

Convert your interval into an NSDate using +dateWithIntervalSince1970, get the date components out of that using NSCalendar's -componentsFromDate method.

SDK Reference

Answer 2

Here's another possibility, somewhat cleaner:

NSDate *date = [NSDate dateWithTimeIntervalSince1970:timeInterval];
NSString *dateStr = [date description];
const char *dateStrPtr = [dateStr UTF8String];

// format: YYYY-MM-DD HH:MM:SS ±HHMM
int year, month, day, hour, minutes, seconds;
sscanf(dateStrPtr, "%d-%d-%d %d:%d:%d", &year, &month, &day, &hour, &minutes, &seconds);
year -= 1970;

Answer 3

- (NSString *)convertTimeFromSeconds:(NSString *)seconds {

    // Return variable.
    NSString *result = @"";

    // Int variables for calculation.
    int secs = [seconds intValue];
    int tempHour    = 0;
    int tempMinute  = 0;
    int tempSecond  = 0;

    NSString *hour      = @"";
    NSString *minute    = @"";
    NSString *second    = @"";

    // Convert the seconds to hours, minutes and seconds.
    tempHour    = secs / 3600;
    tempMinute  = secs / 60 - tempHour * 60;
    tempSecond  = secs - (tempHour * 3600 + tempMinute * 60);

    hour    = [[NSNumber numberWithInt:tempHour] stringValue];
    minute  = [[NSNumber numberWithInt:tempMinute] stringValue];
    second  = [[NSNumber numberWithInt:tempSecond] stringValue];

    // Make time look like 00:00:00 and not 0:0:0
    if (tempHour < 10) {
        hour = [@"0" stringByAppendingString:hour];
    } 

    if (tempMinute < 10) {
        minute = [@"0" stringByAppendingString:minute];
    }

    if (tempSecond < 10) {
        second = [@"0" stringByAppendingString:second];
    }

    if (tempHour == 0) {

        NSLog(@"Result of Time Conversion: %@:%@", minute, second);
        result = [NSString stringWithFormat:@"%@:%@", minute, second];

    } else {

        NSLog(@"Result of Time Conversion: %@:%@:%@", hour, minute, second); 
        result = [NSString stringWithFormat:@"%@:%@:%@",hour, minute, second];

    }

    return result;

}

Answer 4

This code is aware of day light saving times and other possible nasty things.

NSCalendar *gregorianCalendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *components = [gregorianCalendar components: (NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit | NSDayCalendarUnit | NSMonthCalendarUnit | NSYearCalendarUnit )
                                                    fromDate:startDate
                                                      toDate:[NSDate date]
                                                     options:0];


NSLog(@"%ld", [components year]);
NSLog(@"%ld", [components month]);
NSLog(@"%ld", [components day]);
NSLog(@"%ld", [components hour]);
NSLog(@"%ld", [components minute]);
NSLog(@"%ld", [components second]);

Answer 5

From iOS8 and above you can use NSDateComponentsFormatter

It has methods to convert time difference in user friendly formatted string.

NSDateComponentsFormatter *formatter = [[NSDateComponentsFormatter alloc] init];
formatter.unitsStyle = NSDateComponentsFormatterUnitsStyleFull;

NSLog(@"%@", [formatter stringFromTimeInterval:1623452]);

This gives the output - 2 weeks, 4 days, 18 hours, 57 minutes, 32 seconds

Answer 6

Or there is my class method. It doesn't handle years, but that could easily be addedn though it's better for small timelaps like days, hours and minutes. It take plurals into account and only shows what's needed:

+(NSString *)TimeRemainingUntilDate:(NSDate *)date {

    NSTimeInterval interval = [date timeIntervalSinceNow];
    NSString * timeRemaining = nil;

    if (interval > 0) {

        div_t d = div(interval, 86400);
        int day = d.quot;
        div_t h = div(d.rem, 3600);
        int hour = h.quot;
        div_t m = div(h.rem, 60);
        int min = m.quot;

        NSString * nbday = nil;
        if(day > 1)
            nbday = @"days";
        else if(day == 1)
            nbday = @"day";
        else
            nbday = @"";
        NSString * nbhour = nil;
        if(hour > 1)
            nbhour = @"hours";
        else if (hour == 1)
            nbhour = @"hour";
        else
            nbhour = @"";
        NSString * nbmin = nil;
        if(min > 1)
            nbmin = @"mins";
        else
            nbmin = @"min";

        timeRemaining = [NSString stringWithFormat:@"%@%@ %@%@ %@%@",day ? [NSNumber numberWithInt:day] : @"",nbday,hour ? [NSNumber numberWithInt:hour] : @"",nbhour,min ? [NSNumber numberWithInt:min] : @"00",nbmin];
    }
    else
        timeRemaining = @"Over";

    return timeRemaining;
}