problem with between predicate - iphone

Question

when using an nspredicate ( a between predicate) i had an exception.
there is the code i used:
NSMutableArray *returnedArray=[[[NSMutableArray alloc]init] autorelease];
NSManagedObjectContext *context = [self managedObjectContext];
NSEntityDescription *objEntity = [NSEntityDescription entityForName:#"Note" inManagedObjectContext:context];
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
[fetchRequest setEntity:objEntity];
NSSortDescriptor *sortDescriptor = [[NSSortDescriptor alloc] initWithKey:#"When" ascending:YES];
NSArray *sortDescriptors = [NSArray arrayWithObject:sortDescriptor];
[fetchRequest setSortDescriptors:sortDescriptors];
[sortDescriptor release];
NSPredicate *predicate1 = [NSPredicate predicateWithFormat:
#"self.Reunion==%#",reunion];
NSNumber *endOfEtape=[NSNumber numberWithInt:[etape.positionDepart intValue]+[etape.duree intValue]];
NSExpression *s1 = [ NSExpression expressionForConstantValue: etape.positionDepart ];
NSExpression *s2 = [ NSExpression expressionForConstantValue: endOfEtape ];
NSArray *limits = [ NSArray arrayWithObjects: s1, s2, nil ];
NSPredicate *predicate2=[NSPredicate predicateWithFormat: #"self.When BETWEEN %#",limits];
NSPredicate *predicate=[NSCompoundPredicate andPredicateWithSubpredicates:
[NSArray arrayWithObjects:predicate1,predicate2,nil]];
[fetchRequest setPredicate:predicate];
NSArray *notes;
notes=[context executeFetchRequest:fetchRequest error:nil];
[fetchRequest release];
and i had an 'objc_exception_throw' at the line on which i call "executeFetchRequest:" method.
I will be happy if you can help me.
Thanks.

Answer 1

Unfortunately, the BETWEEN operand is considered an aggregate function & these aren't supported by CoreData.
See Apple's Documentation
... consider the BETWEEN operator (NSBetweenPredicateOperatorType); its
right hand side is a collection containing two elements. Using just
the Mac OS X v10.4 API, these elements must be constants, as there is
no way to populate them using variable expressions. On Mac OS X v10.4,
it is not possible to create a predicate template to the effect of
date between {$YESTERDAY, $TOMORROW}; instead you must create a new
predicate each time.
Aggregate expressions are not supported by Core Data.
So you'll need to use a predicate like:
NSPredicate *predicate2 = [NSPredicate predicateWithFormat:
#"self.When >= %# AND self.When <= %#", etape.positionDepart, endOfEtape];
(assuming positionDepart and endOfEtape are of type NSString)