How do I get the next and earlier date of the current date in iPhone sdk

Question

I have a date object,

NSDate *date = [NSDate date];

Now I want a date earlier of this date and next of it. What function should I use.

Earlier and La

Answer 1

You need to use NSCalendar and NSDateComponents to do this calculation reliably.

Here's an example I have to hand to compute an NSDate for noon today. I'm sure you can work out how to get the result you want from this and the documentation.

NSDate *today = [NSDate date];

NSCalendar *gregorian = [[[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar] autorelease];

NSUInteger unitFlags = NSYearCalendarUnit | NSMonthCalendarUnit |  NSDayCalendarUnit;
NSDateComponents* todayComponents = [gregorian components:unitFlags fromDate:today];

todayComponents.hour = 12;

NSDate* noonToday = [gregorian dateFromComponents:todayComponents];