I'm using the following code to convert a user-supplied birthdate to its equivalent years from the current date. The output is always off by an inconsistent amount in years and very large numbers in days and months.
NSDateFormatter *tempFormatter = [[NSDateFormatter alloc] init];
[tempFormatter setDateFormat:#"yyyy-mm-dd hh:mm:ss"];
NSDate *birthDate = [tempFormatter dateFromString:[NSString stringWithFormat:#"%#-%#-%# 01:00:00",self.birthYear.text,self.birthMonth.text,self.birthDay.text]];
NSDate* now = [NSDate date];
NSDateComponents* ageComponents = [[NSCalendar currentCalendar]
components:NSYearCalendarUnit
fromDate:birthDate
toDate:now
options:0];
NSInteger years = [ageComponents year];
NSInteger days = [ageComponents day];
NSInteger months = [ageComponents month];
NSLog(#"Years: %ld, Days: %ld, Months: %ld",years,days, months);
What gets outputted when I input "06-16-1986" is the following
Years: 28, Days: 9223372036854775807, Months: 9223372036854775807
The year is off by 1 and the months and days are producing extremely large numbers. I get the same issue using various dates. For example, "12-07-1989" produces
Years: 25, Days: 9223372036854775807, Months: 9223372036854775807
What am I doing wrong here?
the problem is in this line
NSDateComponents* ageComponents = [[NSCalendar currentCalendar]
components:NSYearCalendarUnit
fromDate:birthDate
toDate:now
options:0];
if you want month & days to be calculated you need to include that in the components like this
NSDateComponents* ageComponents = [[NSCalendar currentCalendar]
components:( NSYearCalendarUnit | NSDayCalendarUnit | NSMonthCalendarUnit)
fromDate:birthDate
toDate:now
options:0];
also your format is wrong for month string
[tempFormatter setDateFormat:#"yyyy-mm-dd hh:mm:ss"];
should be corrected as
[tempFormatter setDateFormat:#"yyyy-MM-dd hh:mm:ss"];
now you will get correct date.
explanation.
as mentioned on apple documentation these are 1-based. so incase you dont provide a value it will put 1 as default. so earlier your month format was "mm" and it was not correctly setting a month for the birthday hence it was 1986-01-16 so now its 2014-04-01 (in singapore). So you get 28 years which is correct.
Add |NSMonthCalendarUnit|NSDayCalendarUnit to your components, change the date format from yyyy-mm-dd hh:mm:ss to yyyy-MM-dd hh:mm:ss:
NSDateFormatter *tempFormatter = [[NSDateFormatter alloc] init];
[tempFormatter setDateFormat:#"yyyy-MM-dd hh:mm:ss"];
NSDate *birthDate = [tempFormatter dateFromString:[NSString stringWithFormat:#"%#-%#-%# 01:00:00",#"2000", #"04",#"01"]];
NSDate* now = [NSDate date];
NSDateComponents* ageComponents = [[NSCalendar currentCalendar]
components:NSYearCalendarUnit|NSMonthCalendarUnit|NSDayCalendarUnit
fromDate:birthDate
toDate:now
options:0];
NSInteger years = [ageComponents year];
NSInteger days = [ageComponents day];
NSInteger months = [ageComponents month];
NSLog(#"Years: %d, Days: %d, Months: %d",years,days, months);
Related
I have a very interesting problem: When calculating the number of days between two dates, my calculator gives the wrong results for the month of March only. I have two text fields, one for each date. If I enter 3/7/12 in date1, and 3/13/12 in date2, the result is 7, which is correct (I am counting the first day as well). But when I enter date1 = 3/7/12 and date2 = 3/14/12, the result is still 7, but it should be 8. Likewise, if I enter date1 = 3/7/12 and date2 = 3/23/12, the result should be 17, but it is 16. If I change the month to April so that date1 = 4/7/12 and date2 = 4/23/12, the result is 17. Every month is working as intended, only the month of March is giving me wrong results. Does anyone have any idea what I am missing? Is this a timezone problem? How do I fix it? Here is my code:
NSDateFormatter *dateFormatter1 = [[NSDateFormatter alloc] init];
[dateFormatter1 setDateFormat:#"MM/dd/yyyy"];
NSDate *startdate1 = [dateFormatter1 dateFromString: date1.text];
NSDateFormatter *dateFormatter2 = [[NSDateFormatter alloc] init];
[dateFormatter2 setDateFormat:#"MM/dd/yyyy"];
NSDate *enddate2 = [dateFormatter2 dateFromString: date2.text];
int start1 = [startdate1 timeIntervalSince1970];
int end2 = [enddate2 timeIntervalSince1970];
double difference12 = end2-start1;
int days12;
days12 =(int)((double)difference12/(3600.0*24.00)+1);
result12.text = [[NSString alloc] initWithFormat:#"%i", days12]
If you use NSCalendar, you won't need to deal with Daylight Savings Time calculation.
int days = [[[NSCalendar currentCalendar] components:NSDayCalendarUnit
fromDate:startDate1
toDate:endDate2
options:0] day] + 1;
Most like this is a daylight savings issue (March 11th, 2012). Set the date formatters' timezones to:
[NSTimeZone timeZoneForSecondsFromGMT:0];
This should fix the issue.
To add to others, please do not rely on number of seconds in a day being 86400 all the time, it won't. Be sure to watch Session 211 Performing Calendar Calculations from WWDC 2011.
You can think of NSDate as a point in time. If you want to calculate number of days between two dates, this is a calendar issue and there are more than one calendars (like the Mayan calendar).
What you need is NSDateComponents:
NSDate *dateToday = [NSDate date];
NSDateComponents *dateBComponent = [[NSDateComponents alloc] init];
[dateBComponent setDay:-10];
NSDate *date10DaysAgo = [[NSCalendar currentCalendar] dateByAddingComponents:dateBComponent
toDate:dateToday
options:0];
NSCalendar *calendar = [[[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar] autorelease];
NSDateComponents *components = [calendar components:NSDayCalendarUnit
fromDate:date10DaysAgo
toDate:dateToday
options:0];
NSLog(#"Difference: %d", components.day);
I am using the following NSCalendar method to get the number of days in a calendar year:
NSRange range = [gregorian rangeOfUnit:NSDayCalendarUnit
inUnit:NSYearCalendarUnit
forDate:date];
I am expecting a range.length return value of type NSRange which is 365 or 366 (days).
However, this code returns a range.length of 31 for a date value of 2005-06-06.
What is wrong with my code?
This is the full code snippet:
NSCalendar *gregorian = [[NSCalendar alloc]
initWithCalendarIdentifier:NSGregorianCalendar];
[subArray enumerateObjectsUsingBlock:
^(NSDate *date, NSUInteger idx, BOOL *stop) {
NSUInteger numberOfDays = [gregorian ordinalityOfUnit:NSDayCalendarUnit
inUnit:NSYearCalendarUnit forDate:date];
}];
This calculates the number of days of a year of a given date:
NSDate *someDate = [NSDate date];
NSDate *beginningOfYear;
NSTimeInterval lengthOfYear;
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
[gregorian rangeOfUnit:NSYearCalendarUnit
startDate:&beginningOfYear
interval:&lengthOfYear
forDate:someDate];
NSDate *nextYear = [beginningOfYear dateByAddingTimeInterval:lengthOfYear];
NSInteger startDay = [gregorian ordinalityOfUnit:NSDayCalendarUnit
inUnit:NSEraCalendarUnit
forDate:beginningOfYear];
NSInteger endDay = [gregorian ordinalityOfUnit:NSDayCalendarUnit
inUnit:NSEraCalendarUnit
forDate:nextYear];
NSInteger daysInYear = endDay - startDay;
Sad caveat: This does not work correctly for year 1582.
The year 1582, the year when Gregor introduced the currently widespread used calendar, needed a fix to align solar with calendar years. So they went with the pragmatic solution: They just dropped October 5-14. (They were not crazy enough to change weekdays, too). As a result the year 1582 only has 355 days.
Addendum: The code above only works correctly for years after 1582. It returns 365 days for the year 1500, for example, even though this year was a leap year in the then used julian calendar. The gregorian calendar starts at October 15, 1582. Computations made on the gregorian calendar are just not defined before that date. So in this way Apple's implementation is correct. I'm not aware of a correct implementation for years before 1583 on Cocoa.
Here's a relatively clean version. It's a category on NSCalendar.
- (NSInteger) daysInYear:(NSInteger) year {
NSDateComponents *dateComponents = [[NSDateComponents alloc] init];
dateComponents.year = year;
dateComponents.month = dateComponents.day = 1;
NSDate *firstOfYear = [self dateFromComponents:dateComponents];
dateComponents.year = year + 1;
NSDate *firstOfFollowingYear = [self dateFromComponents:dateComponents];
return [[self components:NSDayCalendarUnit
fromDate:firstOfYear
toDate:firstOfFollowingYear
options:0] day];
}
Thanks to AKV for pointing out that -components:fromDate:toDate:options will work in this case.
This doesn't seem to work for 1582 or prior, which per Nikolai Ruhe's answer is because Gregorian calendar calculations simply aren't defined prior to then.
What about finding number of days in a given year as: Although this is not the relative solution for the question.
-(NSInteger)daysBetweenTwoDates:(NSDate *)fromDateTime andDate:(NSDate *)toDateTime{
NSDate *fromDate;
NSDate *toDate;
NSCalendar *calendar = [NSCalendar currentCalendar];
[calendar rangeOfUnit:NSDayCalendarUnit startDate:&fromDate interval:NULL forDate:fromDateTime];
[calendar rangeOfUnit:NSDayCalendarUnit startDate:&toDate interval:NULL forDate:toDateTime];
NSDateComponents *difference = [calendar components:NSDayCalendarUnit fromDate:fromDate toDate:toDate options:0];
return [difference day];
}
-(void)someMethod {
NSString *yourYear=#"2012";
NSDate *date1 = [NSDate dateWithString:[NSString stringWithFormat:#"%#-01-01 00:00:00 +0000",yourYear]];
NSDate *date2 = [NSDate dateWithString:[NSString stringWithFormat:#"%#-12-31 00:00:00 +0000",yourYear]];
NSInteger numberOfDays=[self daysBetweenTwoDates:date1 andDate:date2];
NSLog(#"There are %ld days in between the two dates.", numberOfDays);
}
Edit:
As dateWithString: is deprecated, you can use
NSDateFormatter *dateFormatter=[[NSDateFormatter alloc] init];
[dateFormatter dateFormat]=#"dd-MM-yyyy";
NSDate *date=[dateFormatter dateFromString:dateString];
to form date1 and date2
You are getting the number of days in the month of your date.
You could use the same function and just pass in a date with February as the month. If range.length returns 28, the Total days in the year will be 365, if it returns 29, then the number of days will be 366.
I would like to use the date of the weekends to use it in the NSLocalNotification, but i don't how to get it, i tried to do it mathematically, but sometimes i gets a number greater than the days of the month.
Note that iOS supports several Calendars, I am not sure, if all cultures that uses those calendars have a concept of weekends and if they are always meant to have two days.
Something you also needs to deal with: even in countries that uses the Gregorian calendar a week might start with monday or sunday.
But if we assume that a weekend are equivalent to saturday and sunday, this might be helpful for you:
NSDate *referenceDate = [NSDate date];
NSDate *startOfThisWeek;
NSDate *saturday;
NSUInteger backupStartWeekday = [[NSCalendar currentCalendar] firstWeekday];
[[NSCalendar currentCalendar] setFirstWeekday:1]; // ensure week begins at sunday
[[NSCalendar currentCalendar] rangeOfUnit:NSWeekCalendarUnit
startDate:&startOfThisWeek
interval:NULL
forDate:referenceDate];
NSDateComponents *components = [[NSDateComponents alloc] init];
components.day = [[NSCalendar currentCalendar] maximumRangeOfUnit:NSWeekdayCalendarUnit].length; //the start of the next week
components.day = components.day - 2;
saturday = [[NSCalendar currentCalendar] dateByAddingComponents:components
toDate:startOfThisWeek
options:0];
[[NSCalendar currentCalendar] setFirstWeekday:backupStartWeekday];
Your first problem about getting the date can be solved as :
NSCalendar *calender=[NSCalendar currentCalendar];
NSRange daysRange=[calender rangeOfUnit:NSDayCalendarUnit inUnit:NSMonthCalendarUnit forDate:[NSDate date]];
NSUInteger numberOfDaysInMonth=daysRange.length;
//NSLog(#"num of days in current month : %ld",numberOfDaysInMonth);
NSDateComponents *dateComponents = [calender components:NSWeekdayCalendarUnit fromDate:[NSDate date]];
NSInteger dayCount=[dateComponents weekday];
//if today itself is saturday what you want to display? today or upcoming one... then do small changes here, for sat & sun.
NSInteger daysForSaturday=7-dayCount;
NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
[formatter setDateFormat:#"dd"];
NSUInteger todaysDate = [[formatter stringFromDate:[NSDate date]]integerValue];
// NSLog(#"Today is : %#",todaysDate);
NSUInteger comingSaturday=todaysDate+daysForSaturday;
if (comingSaturday>numberOfDaysInMonth) {
comingSaturday-=numberOfDaysInMonth;
}
NSUInteger comingSunday=comingSaturday+1;
NSLog(#"Coming.. Sat is : %ld, Sun in : %ld",comingSaturday, comingSunday);
I need to change a NSDate object. What I am basically doing is changing the year value.
for example:
NSString *someYear = #"2093";
NSDate *date = [NSDate date]; // Gets the current date.
... Create a new date based upon 'date' but with specified year value.
So with 'date' returning 2011-03-06 22:17:50 +0000 from init, I would like to create a date with 2093-03-06 22:17:50 +0000.
However I would like this to be as culturally neutral as possible, so it will work whatever the timezone.
Thanks.
Here's my code for setting the UIDatePicker limits for a Date Of Birth selection. Max age allowed is 100yrs
_dateOfBirth.maximumDate = [NSDate date];
//To limit the datepicker year to current year -100
NSDate *currentDate = [NSDate date];
NSUInteger componentFlags = NSYearCalendarUnit;
NSDateComponents *components = [[NSCalendar currentCalendar] components:componentFlags fromDate:currentDate];
NSInteger year = [components year];
NSLog(#"year = %d",year);
[components setYear:-100];
NSDate *minDate = [[NSCalendar currentCalendar] dateByAddingComponents:components toDate:currentDate options:0];
_dateOfBirth.minimumDate = minDate;
Take a look at NSCalendar, especially components:fromDate: and dateFromComponents: methods.
I managed to figure the answer with the pointer Hoha gave me.
NSNumber *newYear = [[NSNumber alloc] initWithInt:[message intValue]];
NSCalendar* gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
unsigned int unitFlags = NSYearCalendarUnit | NSDayCalendarUnit | NSMonthCalendarUnit;
NSDateComponents* dateComponents = [gregorian components:unitFlags fromDate:[NSDate date]];
[dateComponents setYear:[newYear intValue]];
NSDate *newDate = [gregorian dateFromComponents:dateComponents];
[newYear release];
Starting in iOS 8 you can set an specific date component. For example:
date = [calendar dateBySettingUnit:NSCalendarUnitYear value:year ofDate:date options:0];
I would like to work out the difference in months
at the moment I have this code:
dateInterval = [endDate timeIntervalSinceDate:startDate];
But that returns a value in seconds, I would like to see the difference between the dates in months.
How would I do this?
Thanks
NSDateFormatter *inputFormatter = [[NSDateFormatter alloc] init];
[inputFormatter setDateFormat:#"dd/MM/yyyy"];
NSDate *startDate = [inputFormatter dateFromString:#"07/03/2011"];
NSDate *endDate = [inputFormatter dateFromString:#"07/06/2011"];
NSInteger month_delta = [[[NSCalendar currentCalendar] components: NSMonthCalendarUnit fromDate: startDate toDate: endDate options: 0] month];
NSLog(#"---------------------------->>%d", month_delta);
[inputFormatter release]; // <-- in case not using ARC
it will log:
---------------------------->>3
You can create a NSDateComponents from the NSDates in question and just subtract the total months. (Total months = 12*year+currentMonth)
http://developer.apple.com/library/mac/#documentation/Cocoa/Reference/Foundation/Classes/NSDateComponents_Class/Reference/Reference.html#//apple_ref/occ/cl/NSDateComponents