Creating an NSDate based on later date

Question

I am trying to create an NSDate object with a certain number of hours and minutes before a reference date.

For example:

Reference date = oct 21 2013 12:30 PM

date with 2 hours before and 40 minute before: oct 21 2013 9:50 AM

Is it possible to do this?

score 1 · Answer 1 · answered Oct 26 '13 at 22:26

1

You can use NSDate method dateByAddingTimeInterval. It takes a NSTimeInterval double to add the number of seconds to the desired time. Check NSDate class, there are other method of interest for you. NSDate

answered Oct 26 '13 at 22:26

J2theC

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But i don't want to add a time interval, I want to subtract one. Would it work if i made it a negative number? – flux Oct 26 '13 at 22:28
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@user2113952: Did you try it? – Martin R Oct 26 '13 at 22:29
Yes also it says in the documentation – flux Oct 26 '13 at 22:31
I was looking for a method like dateBySubtractingTimeInterval: and didnt think of using a negative number – flux Oct 26 '13 at 22:31

score 1 · Answer 2 · answered Oct 26 '13 at 23:06

Use NSDateComponents.

NSDateComponents *dateComps = [[NSCalender currentCalender] components:(NSDayCalenderUnit | NSMonthCalenderUnit | NSYearCalenderUnit | NSHourCalenderUnit | NSMinuteCalenderUnit | NSSecondCalenderUnit) fromDate:now];
[dateComps setHour:[dateComps hour]-2]; // Subtract here
[dateComps setMinute:[dateComps minute]-40]; // Subtract here

// You can change all components here as above methods.

NSDate *dateResult=[[NSCalender currentCalender] dateFromComponents:dateComps];

NSLog("%@",dateResult);

This is in fact the better way to do date arithmetic, because it takes into account the vagaries of calendars and time zones. — jscs, Oct 26 '13 at 23:16

Creating an NSDate based on later date

2 Answers2