Question

I have a core data context with objects that have a date stored in them. I would like to get the data for only the current week (Monday to Sunday) in that order. I am not looking for the last 7 days.

The date could be the one stored inside the entity or the data of when the object was added to core data (they are the same).

I can use a predicate with a start date and end date like this:

NSPredicate *weekPredicate = [NSPredicate predicateWithFormat:@"((date > %@) AND (date <= %@)) || (date = nil)",startDate,endDate];

but how do I calculate startDate and endDate?

Answer 1

-(NSDate *) lastMondayBeforeDate:(NSDate*)timeStamp {
   NSCalendar *gregorian = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
   NSDateComponents *comps = 
      [gregorian components:NSWeekdayCalendarUnit fromDate:timeStamp];
   NSInteger weekday = [comps weekday];
   weekday = weekday==1 ? 6 : weekday-2; // start with 0 on Monday rather than 1 on Sunday
   NSTimeInterval secondsSinceMondayMidnight =  
     (NSUInteger) [timeStamp timeIntervalSince1970] % 60*60*24 + weekday * 60*60*24;
   return [timeStamp dateByAddingTimeInterval:-secondsSinceMondayMidnight];
}

-(NSDate *) nextMondayAfterDate:(NSDate*)timeStamp {
   return [[self lastMondayBeforeDate:timeStamp] 
      dateByAddingTimeInterval:60*60*24*7];
}