Modifying NSDate to represent 1 month from today
Solution 1
(Almost the same as this question.)
From the documentation:
Use of NSCalendarDate strongly discouraged. It is not deprecated yet, however it may be in the next major OS release after Mac OS X v10.5. For calendrical calculations, you should use suitable combinations of NSCalendar, NSDate, and NSDateComponents, as described in Calendars in Dates and Times Programming Topics for Cocoa.
Following that advice:
NSDate *today = [NSDate date];
NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *components = [[NSDateComponents alloc] init];
components.month = 1;
NSDate *nextMonth = [gregorian dateByAddingComponents:components toDate:today options:0];
[components release];
NSDateComponents *nextMonthComponents = [gregorian components:NSYearCalendarUnit | NSMonthCalendarUnit fromDate:nextMonth];
NSDateComponents *todayDayComponents = [gregorian components:NSDayCalendarUnit fromDate:today];
nextMonthComponents.day = todayDayComponents.day;
NSDate *nextMonthDay = [gregorian dateFromComponents:nextMonthComponents];
[gregorian release];
There may be a more direct or efficient implementation, but this should be accurate and should point in the right direction.
Solution 2
Use NSCalender, NSDateComponents and NSDate:
NSDateComponents *components = [[[NSDateComponents alloc] init] autorelease];
components.month = 1;
NSDate *oneMonthFromNow = [[NSCalendar currentCalendar] dateByAddingComponents:components toDate:[NSDate date] options:0];
Just set the different properties of components
to get different periods of time (e.g. 3 months, 6 months etc).
Note: Depending on the context, you may want to use [[[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar] autorelease]
instead of [NSCalendar currentCalendar]
, if by "1 month" you mean "1 month on the Gregorian calendar".
bmalicoat
I'm a current CS student at Michigan State University. I have released 5 games and applications for T-Mobile's Sidekick and 1 application for Apple's iPhone. My main interests are game development and mobile software development.
Updated on July 17, 2020Comments
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bmalicoat almost 4 years
I'm adding repeating events to a Cocoa app I'm working on. I have repeat every day and week fine because I can define these mathematically (3600*24*7 = 1 week). I use the following code to modify the date:
[NSDate dateWithTimeIntervalSinceNow:(3600*24*7*(weeks))]
I know how many months have passed since the event was repeated but I can't figure out how to make an NSDate object that represents 1 month/3 months/6 months/9 months into the future. Ideally I want the user to say repeat monthly starting Oct. 14 and it will repeat the 14th of every month.
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mmalc over 15 yearsThe documentation makes clear that NSCalendarDate should not be used.
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oberbaum over 14 yearsuse of the NSCalendarDate is generally not accepted for iPhone Apps.
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lagos almost 12 yearsIs better to use NSDateCompontents and setMonth to +1. Then you get same date but in next month.
NSDateComponents *components = [gregorian components: NSYearCalendarUnit|NSMonthCalendarUnit|NSDayCalendarUnit fromDate:[NSDate date]]; [components setMonth://here you set current month+1]; NsDate *nextMonth = [gregorian dateFromComponents:components];
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Jack Humphries almost 11 yearsI don't have a device to test with right now, but what would happen if you go forward by one month on January 29 if it's not a leap year? Would the day be February 28 or March 1?