core data - NSPredicate BETWEEN with NSDate causes -[__NSDate constantValue]: unrecognized selector sent to instance 0x1e7ff0

Question

I'm trying to fetch from Core Data records that have a startTime between two dates.

Here's my code:

NSDate *today = [NSDate date];
NSDate *distantFuture = [NSDate distantFuture];

// Create the predicate
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"startTime BETWEEN %@", [NSArray arrayWithObjects:today, distantFuture, nil]];

NSLog(@"today: %@, distantFuture: %@", today, distantFuture);   
NSLog(@"predicate: %@", predicate);

// Add the predicate to the fetchRequest
[[[self fetchedResultsController] fetchRequest] setPredicate:predicate];

NSError *error;
if (![[self fetchedResultsController] performFetch:&error]) 
{
    // Update to handle the error appropriately.
    NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
    exit(-1);  // Fail
}

And here's the console output:

2011-03-11 02:00:03.166 TestApp[2668:307] today: 2011-03-11 01:00:03 AM +0000, distantFuture: 4001-01-01 12:00:00 AM +0000
2011-03-11 02:00:03.174 TestApp[2668:307] predicate: startTime BETWEEN {2011-03-11 01:00:03 AM +0000, 4001-01-01 12:00:00 AM +0000}
2011-03-11 02:00:03.180 TestApp[2668:307] -[__NSDate constantValue]: unrecognized selector sent to instance 0x1e7ff0
2011-03-11 02:00:03.198 TestApp[2668:307] *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSDate constantValue]: unrecognized selector sent to instance 0x1e7ff0'
*** Call stack at first throw:
(
    0   CoreFoundation                      0x314d0987 __exceptionPreprocess + 114
    1   libobjc.A.dylib                     0x319a149d objc_exception_throw + 24
    2   CoreFoundation                      0x314d2133 -[NSObject(NSObject) doesNotRecognizeSelector:] + 102
    3   CoreFoundation                      0x31479aa9 ___forwarding___ + 508
    4   CoreFoundation                      0x31479860 _CF_forwarding_prep_0 + 48
    5   CoreData                            0x352ed973 -[NSSQLSimpleWhereIntermediate _generateSQLBetweenStringInContext:] + 766
    6   CoreData                            0x35244fff -[NSSQLSimpleWhereIntermediate generateSQLStringInContext:] + 502
    7   CoreData                            0x35244647 -[NSSQLFetchIntermediate generateSQLStringInContext:] + 74
    8   CoreData                            0x352e42b3 -[NSSQLGenerator newSQLStatementForFetchRequest:ignoreInheritance:countOnly:nestingLevel:] + 234
    9   CoreData                            0x352414ab -[NSSQLAdapter _newSelectStatementWithFetchRequest:ignoreInheritance:] + 378
    10  CoreData                            0x35241329 -[NSSQLAdapter newSelectStatementWithFetchRequest:] + 16
    11  CoreData                            0x35241205 -[NSSQLCore newRowsForFetchPlan:] + 288
    12  CoreData                            0x35240531 -[NSSQLCore objectsForFetchRequest:inContext:] + 420
    13  CoreData                            0x35240151 -[NSSQLCore executeRequest:withContext:error:] + 304
    14  CoreData                            0x352d0295 -[NSPersistentStoreCoordinator executeRequest:withContext:error:] + 896
    15  CoreData                            0x3523d877 -[NSManagedObjectContext executeFetchRequest:error:] + 374
    16  CoreData                            0x352f541b -[NSFetchedResultsController performFetch:] + 766
    17  TestApp                             0x0001ac6d -[MatchesCalendarDataSource loadMatchesFrom:to:delegate:] + 268
    18  TestApp                             0x0001ad51 -[MatchesCalendarDataSource presentingDatesFrom:to:delegate:] + 68
    19  TestApp                             0x00021353 -[KalViewController reloadData] + 110
    20  TestApp                             0x00021b15 -[KalViewController loadView] + 452
    21  UIKit                               0x338dc227 -[UIViewController view] + 30
    22  UIKit                               0x338e8d0b -[UIViewController contentScrollView] + 22
    23  UIKit                               0x338e8b7b -[UINavigationController _computeAndApplyScrollContentInsetDeltaForViewController:] + 30
    24  UIKit                               0x338e8a79 -[UINavigationController _layoutViewController:] + 24
    25  UIKit                               0x338e84d3 -[UINavigationController _startTransition:fromViewController:toViewController:] + 254
    26  UIKit                               0x338e835f -[UINavigationController _startDeferredTransitionIfNeeded] + 182
    27  UIKit                               0x338e82a3 -[UINavigationController viewWillLayoutSubviews] + 14
    28  UIKit                               0x338e823f -[UILayoutContainerView layoutSubviews] + 138
    29  UIKit                               0x338b10cf -[UIView(CALayerDelegate) layoutSublayersOfLayer:] + 26
    30  CoreFoundation                      0x3146ebbf -[NSObject(NSObject) performSelector:withObject:] + 22
    31  QuartzCore                          0x30a6c685 -[CALayer layoutSublayers] + 120
    32  QuartzCore                          0x30a6c43d CALayerLayoutIfNeeded + 184
    33  QuartzCore                          0x30a6656d _ZN2CA7Context18commit_transactionEPNS_11TransactionE + 212
    34  QuartzCore                          0x30a66383 _ZN2CA11Transaction6commitEv + 190
    35  QuartzCore                          0x30a89f9d _ZN2CA11Transaction17observer_callbackEP19__CFRunLoopObservermPv + 52
    36  CoreFoundation                      0x31460c59 __CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__ + 16
    37  CoreFoundation                      0x31460acd __CFRunLoopDoObservers + 412
    38  CoreFoundation                      0x314580cb __CFRunLoopRun + 854
    39  CoreFoundation                      0x31457c87 CFRunLoopRunSpecific + 230
    40  CoreFoundation                      0x31457b8f CFRunLoopRunInMode + 58
    41  GraphicsServices                    0x35d664ab GSEventRunModal + 114
    42  GraphicsServices                    0x35d66557 GSEventRun + 62
    43  UIKit                               0x338d5329 -[UIApplication _run] + 412
    44  UIKit                               0x338d2e93 UIApplicationMain + 670
    45  TestApp                             0x000029d7 main + 70
    46  TestApp                             0x00002958 start + 52
)
terminate called after throwing an instance of 'NSException'

I've also tried the predicate below, which uses >= AND <= instead of the BETWEEN statement (see below). This doesn't cause an error but neither does it fetch any records!

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"(startTime >= %@) AND (startTime <= %@)", today, distantFuture];

As a test I've tried a predicate that doesn't include NSDate objects and it works fine (see below):

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"location.title == %@", @"Boston"];

Any help or advice would be much appreciated.

Many thanks, Matthew

---

Edit

Thanks for your help Dave.

So now I'm back to using the <= construct but I'm getting 0 objects fetched.

I was just using today and distantFuture as a test to make absolutely sure that my startTime would be between those dates. In the real code it's a range from fromDate to toDate.

Here's my NSPredicate:

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"( ( %@ <= %K ) && ( %K <= %@ ) )", fromDate, @"startTime", @"startTime", toDate];

Here's the console output:

predicate: CAST(336261600.000000, "NSDate") <= startTime AND startTime <= CAST(339285599.000000, "NSDate")
[sectionInfo numberOfObjects]: 0

Here are the dates that are in Core Data (the Attribute Type is set to Date):

startTime
---------
337249800
337309200
337318200

I have no idea why 0 objects are returned. Can anyone see where I'm going wrong?

Answer 1

According to the documentation, the BETWEEN operator counts as an aggregate expression, and ...

Aggregate expressions are not supported by Core Data.

So yes, in order to work around this, you must use the >= and <= construction.

However, given that one of your dates is [NSDate distantFuture], you don't need the "less than" comparison at all. You should be able to do:

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"startTime >= %@", [NSDate date]];