NSDate, NSCalendar and NSDateComponents timing

Question

NSDate *today = [NSDate date];
NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
[calendar setTimeZone:[NSTimeZone timeZoneWithName:@"GMT+2"]];

NSDateComponents *dateComponents = [calendar components:(NSDayCalendarUnit | NSWeekdayCalendarUnit) fromDate:today];    

NSInteger day = [dateComponents day];
NSInteger month = [dateComponents month];
NSInteger year = [dateComponents year];

 NSLog(@" %i %i %i ", day, month, year);

That code show me "12 2147483647 2147483647"

How can I get the month and year (integer)

How can add/forward one day? (if we are the first of the month too!)

Thant you for your attention :-)

score 9 · Accepted Answer · answered Apr 12 '11 at 11:24

NSCalendar *calendar= [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSCalendarUnit unitFlags = NSYearCalendarUnit | NSMonthCalendarUnit |  NSDayCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit;
NSDate *date = [NSDate date];
NSDateComponents *dateComponents = [calendar components:unitFlags fromDate:date];

NSInteger year = [dateComponents year];
NSInteger month = [dateComponents month];
NSInteger day = [dateComponents day];
NSInteger hour = [dateComponents hour];
NSInteger minute = [dateComponents minute];
NSInteger second = [dateComponents second];

[calendar release];

hope this helps

thanks for the help, I just have to code the second question; add/substract a day ^^ — clement, Apr 12 '11 at 12:16

Steven Kramer · Answer 2 · 2011-04-12T11:31:44.900

2

Add more units to NSDayCalendarUnit | NSWeekdayCalendarUnit - you are not requesting month or year, therefore they are invalid!
Add/subtract a NSDateComponents object configured for 1 day and [NSCalendar dateByAddingComponents:toDate:options:]. Alternatively, and probably just as correct, use [NSDate dateWithTimeInterval:sinceDate:]

edited Apr 12 '11 at 11:31

answered Apr 12 '11 at 10:59

Steven Kramer

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Great, please accept the answer so people will be able to find it... did you get the point about `dateByAddingComponents`? – Steven Kramer Apr 12 '11 at 11:32
1

Don't try value based coding in Cocoa - everything is a reference (i.e. a pointer to an object). Use `NSDate* newDate = [calendar dateByAddingComponents: oneDay toDate: self.date options: 0];` – Steven Kramer Apr 12 '11 at 14:39
Are you sure? You might want to measure this first, tons of objects are getting created all the time in most apps. – Steven Kramer Apr 12 '11 at 15:23
1

Don't worry. Your users can't swipe quickly enough to notice the object creation. Up to a few thousand object creations/deallocations per second (at least!) should not be noticeable. – Steven Kramer Apr 12 '11 at 15:55

NSDate, NSCalendar and NSDateComponents timing

2 Answers2