[Image count]: unrecognized selector sent to instance

Question

I get the following error when saving managedObjectContext:

Terminating app due to uncaught exception 'NSInvalidArgumentException', 
reason: '-[Image count]: unrecognized selector sent to instance

Code:

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingImage:(UIImage *)selectedImage editingInfo:(NSDictionary *)editingInfo {

// Delete any existing image.
Image *oldImage = _place.image;
if (oldImage != nil) {
    [_place.managedObjectContext deleteObject:oldImage];
}

Image *image = [NSEntityDescription insertNewObjectForEntityForName:@"Image" inManagedObjectContext:_place.managedObjectContext];
image.imageData = UIImageJPEGRepresentation(selectedImage, 0.5);
_place.image = image;
[_place.managedObjectContext save:nil]; //Here is the crash
[self dismissViewControllerAnimated:YES completion:nil];

Image entity has two one-to-one relationships: place and trip.

@interface Image : NSManagedObject

@property (nonatomic, retain) NSData * imageData;
@property (nonatomic, retain) Trip *trip;
@property (nonatomic, retain) Place *place;

@end

Can't understand why [Image count] error comes out on one-to-one relationship.

Upd.:

@interface Place : NSManagedObject

@property (nonatomic, retain) NSString * address;
@property (nonatomic, retain) NSString * name;
@property (nonatomic, retain) id thumbnail;

@property (nonatomic, retain) Image *image;

@end

Upd.2:

*** First throw call stack:
(
    0   CoreFoundation                      0x022935e4 __exceptionPreprocess + 180
    1   libobjc.A.dylib                     0x01cef8b6 objc_exception_throw + 44
    2   CoreFoundation                      0x02330903 -[NSObject(NSObject) doesNotRecognizeSelector:] + 275
    3   CoreFoundation                      0x0228390b ___forwarding___ + 1019
    4   CoreFoundation                      0x022834ee _CF_forwarding_prep_0 + 14
    5   CoreData                            0x00803df8 -[NSSQLCore _knownOrderKeyForObject:from:inverseToMany:] + 200
    6   CoreData                            0x0073ad50 -[NSSQLCore _populateRowForOp:withObject:] + 1120
    7   CoreData                            0x00750e27 -[NSSQLCore recordValuesForInsertedObject:] + 71
    8   CoreData                            0x00739b5d -[NSSQLCore recordChangesInContext:] + 685
    9   CoreData                            0x00738925 -[NSSQLCore saveChanges:] + 565
    10  CoreData                            0x0070555c -[NSSQLCore executeRequest:withContext:error:] + 412
    11  CoreData                            0x00705050 -[NSPersistentStoreCoordinator executeRequest:withContext:error:] + 4704
    12  CoreData                            0x00731ccc -[NSManagedObjectContext save:] + 764
    13  Travel Plan                         0x0001cf12 -[PlaceViewController imagePickerController:didFinishPickingImage:editingInfo:] + 738
    14  UIKit                               0x00cd5e6c -[UIImagePickerController _imagePickerDidCompleteWithInfo:] + 488
    15  PhotoLibrary                        0x13694e94 PLNotifyImagePickerOfImageAvailability + 106
    16  PhotosUI                            0x14411585 -[PUUIPhotosAlbumViewController handleNavigateToAsset:inContainer:] + 401
    17  PhotosUI                            0x143947b4 -[PUPhotosGridViewController collectionView:shouldSelectItemAtIndexPath:] + 577
    18  UIKit                               0x0106dc0b -[UICollectionView _selectItemAtIndexPath:animated:scrollPosition:notifyDelegate:] + 173
    19  UIKit                               0x010861f8 -[UICollectionView _userSelectItemAtIndexPath:] + 189
    20  UIKit                               0x010863b5 -[UICollectionView touchesEnded:withEvent:] + 437
    21  libobjc.A.dylib                     0x01d01874 -[NSObject performSelector:withObject:withObject:] + 77
    22  UIKit                               0x00bb6902 forwardTouchMethod + 271
    23  UIKit                               0x00bb6972 -[UIResponder touchesEnded:withEvent:] + 30
    24  libobjc.A.dylib                     0x01d01874 -[NSObject performSelector:withObject:withObject:] + 77
    25  UIKit                               0x00bb6902 forwardTouchMethod + 271
    26  UIKit                               0x00bb6972 -[UIResponder touchesEnded:withEvent:] + 30
    27  libobjc.A.dylib                     0x01d01874 -[NSObject performSelector:withObject:withObject:] + 77
    28  UIKit                               0x00bb6902 forwardTouchMethod + 271
    29  UIKit                               0x00bb6972 -[UIResponder touchesEnded:withEvent:] + 30
    30  UIKit                               0x00dd1c7f _UIGestureRecognizerUpdate + 7166
    31  UIKit                               0x00a9c19a -[UIWindow _sendGesturesForEvent:] + 1291
    32  UIKit                               0x00a9d0ba -[UIWindow sendEvent:] + 1030
    33  UIKit                               0x00a70e86 -[UIApplication sendEvent:] + 242
    34  UIKit                               0x00a5b18f _UIApplicationHandleEventQueue + 11421
    35  CoreFoundation                      0x0221c83f __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ + 15
    36  CoreFoundation                      0x0221c1cb __CFRunLoopDoSources0 + 235
    37  CoreFoundation                      0x0223929e __CFRunLoopRun + 910
    38  CoreFoundation                      0x02238ac3 CFRunLoopRunSpecific + 467
    39  CoreFoundation                      0x022388db CFRunLoopRunInMode + 123
    40  GraphicsServices                    0x046299e2 GSEventRunModal + 192
    41  GraphicsServices                    0x04629809 GSEventRun + 104
    42  UIKit                               0x00a5dd3b UIApplicationMain + 1225
    43  Travel Plan                         0x0004c53d main + 141
    44  libdyld.dylib                       0x02dd170d start + 1
)

Answer 1

I got exactly the same problem after changing some relations in my models. This seems to be a bug in Xcode that appears when you change a relationship that was "to many : ordered" to a "to one" relation. It's like Xcode still thinks that the relation is to many because the "ordered" tick-box is ticked.

A very easy solution to solve this is to change back to a "to many" relationship, unselect "ordered" and then change it back again to a "to one" relation.

Answer 2

That was some bug in Xcode. After setting relationship to many, and then back to one, it started to work without errors.