macOS Set time on existing NSDate object

[goedsole]

Dear Y'all -

I've got an NSDate object and want to change it's value to a hard-coded time (12:00am) while leaving the date as is. This doesn't seem like it would be hard, but experimenting and searching have not helped.

Any help is appreciated.

- Billy

 

[lee1210]

NSDate is immutable, so you'll need to create a new one, you can't alter one you already have.

NSTimeInterval oldInterval = [myDate timeIntervalSinceReferenceDate];
double secondsSinceMidnight = fmod(oldInterval,86400.0);
NSDate *myNewDate = [NSDate dateWithTimeIntervalSinceReferenceDate:(oldInterval - secondsSinceMidnight)];

Assuming the date you want to "modify" is myDate, i think this should do it. I haven't tested this at all.

-Lee

EDIT: You could also get a new date by getting the seconds since midnight as a negative number, then send dateByAddingTimeInterval: to your original date with the negative seconds as your parameter.

EDIT 2: It may be easier to use NSCalendar:

NSCalendar *gregorian = [[NSCalendar alloc]
    initWithCalendarIdentifier:NSGregorianCalendar];
NSDateComponents *comp = [gregorian components:  (NSYearCalendarUnit | NSMonthCalendarUnit |  NSDayCalendarUnit) fromDate: myDate];
NSDate *myNewDate = [gregorian dateFromComponents:comps];
[comps release];
[gregorian release];

 

[goedsole]

Perfect!

Thanks.

- Billy