Question

I’m having a problem with Core Data. I have two Entities (Article and Manufacturer) (one containing a transformable attribute which is an array of the other entity). Everything’s working fine till I try to add the array to the NSManagedObject. Here’s some code:

@implementation HASArticleInitializer

- (void)initialize:(NSArray *)initArray {
    //Alloc and init some local variables
    NSMutableArray *articleEntitiesArray = [NSMutableArray alloc] init];
    for (NSInteger pageIndex = 1; pageIndex <= pageCount; pageIndex++) {

        //Parsing the website

        //For-loop for every object on every page
        for (NSInteger object = 0; object < [articleNumbersOnOnePageArray count]; object++) {
            //Doing other string manipulation and parsing stuff


            NSManagedObject *newArticleEntry = [NSEntityDescription insertNewObjectForEntityForName:@"Article"inManagedObjectContext:context];

            [newArticleEntry setValue:[NSString stringWithFormat:@"%@_%@", manufacturerNumber, articleNumber] forKey:@"number"];
            [newArticleEntry setValue:articleTextComplete forKey:@"text"];
            [newArticleEntry setValue:articleStatus forKey:@"status"];
            [newArticleEntry setValue:manufacturerName forKey:@"manufacturerName"];
            [newArticleEntry setValue:manufacturerNumber forKey:@"manufacturerID"];

            [articleEntitiesArray addObject:newArticleEntry];
        }
    }

    NSManagedObject *newManufacturerEntry = [NSEntityDescription insertNewObjectForEntityForName:@"Manufacturer" inManagedObjectContext:context];

    //Encoding the NSArray and setting the entity attribute to Binary Data doesn't work neither
    //NSData *arrayData = [NSKeyedArchiver archivedDataWithRootObject:articleEntitiesArray];

    [newManufacturerEntry setValue:manufacturerName forKey:@"name"];
    [newManufacturerEntry setValue:manufacturerNumber forKey:@"manufacturerID"];
    [newManufacturerEntry setValue:manufacturerCount forKey:@"count"];
    [newManufacturerEntry setValue:articleEntitiesArray forKey:@"articles"];
    NSLog(@"%@", articleEntitiesArray);
}


@end

I tried everything I thought it could or couldn’t help, I’ve really spend days on this, but I always get the following error when the AppDelegate’s - (IBAction)saveAction:(id)sender method is called:

[15836:a057] -[NSManagedObject encodeWithCoder:]: unrecognized selector sent to instance 0x1001896e0
[15836:a057] An uncaught exception was raised
[15836:a057] -[NSManagedObject encodeWithCoder:]: unrecognized selector sent to instance 0x1001896e0
[15836:a057] (
0   CoreFoundation                      0x00007fff8dc94716 __exceptionPreprocess + 198
1   libobjc.A.dylib                     0x00007fff8bfe6470 objc_exception_throw + 43
2   CoreFoundation                      0x00007fff8dd2ad5a -[NSObject(NSObject) doesNotRecognizeSelector:] + 186
3   CoreFoundation                      0x00007fff8dc82c3e ___forwarding___ + 414
4   CoreFoundation                      0x00007fff8dc82a28 _CF_forwarding_prep_0 + 232
5   Foundation                          0x00007fff86931401 _encodeObject + 1163
6   Foundation                          0x00007fff869323cc -[NSKeyedArchiver _encodeArrayOfObjects:forKey:] + 410
7   Foundation                          0x00007fff869320c9 -[NSArray(NSArray) encodeWithCoder:] + 473
8   Foundation                          0x00007fff86931401 _encodeObject + 1163
9   Foundation                          0x00007fff869358f9 +[NSKeyedArchiver archivedDataWithRootObject:] + 182
10  iLoadPix                            0x0000000100003c21 -[HASArticleInitializer initialize:] + 3793
11  Foundation                          0x00007fff86926842 __NSThread__main__ + 1345
12  libsystem_c.dylib                   0x00007fff88553782 _pthread_start + 327
13  libsystem_c.dylib                   0x00007fff885401c1 thread_start + 13

Core Data Model:
Entity 1
Entity 2

As I said, everything works fine if I don’t save the array, the NSLog is correct, too. If it matters I use NSThreads (but I don’t think so because everything else works just fine) 🙁

Please help me! Thanks so much in advance! 🙁

Answer 1

Transformable properties are archived via keyed archiving/unarchiving… however NSManagedObject isn’t designed to be archived this way. (It doesn’t implement the NSCoding protocol.)

To get around this you could turn your managed objects into dictionary representations, but the most natural thing seems to be to use a core data relationship between the 2 entities. Is there a reason you didn’t model a relationship here?