Core Data Crash in the subclass of NSManagedObject

Question

Created Apr ’16

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APPNameCoreDataEvent is the subclass of NSManagedObject. The crash happend in the property of APPNAMEEvent. What's wrong with it ??

Is there something that I missuse??

@class APPNAMECoreDataHeader;
@protocol APPNAMEPersistent
@property (nonatomic,strong) NSObject *model;
@end

@interface APPNameCoreDataEvent : NSManagedObject <APPNAMEEvent,APPNAMEPersistent>
/
*  subclass of NSManagedObject
*/
@property (nonatomic, retain) APPNAMECoreDataHeader * header;
@property (nonatomic,strong) APPNAMEEvent *model;
@end

Here's the Crash Log:

Thread 36 Crashed:
0   CoreData                            snapshot_get_value_as_object + 68
1   CoreData                            _PF_Handler_Public_GetProperty + 83
2   APPName                            -[APPNameCoreDataEvent model] (APPNameCoreDataEvent.m:35)
3   APPName                            __54-[APPNameCoreDataManager removeHistoryAnalytics:]_block_invoke (APPNameCoreDataManager71)
4   CoreData                            developerSubmittedBlockToNSManagedObjectContextPerform + 179
5   libdispatch.dylib                   _dispatch_queue_drain + 1763
6   libdispatch.dylib                   _dispatch_queue_invoke + 283
7   libdispatch.dylib                   _dispatch_root_queue_drain + 1573
8   libdispatch.dylib                   _dispatch_worker_thread3 + 95
9   libsystem_pthread.dylib             _pthread_wqthread + 1025
10  libsystem_pthread.dylib             start_wqthread + 8

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Answer 1

NotMyName OP

Apr ’16

What's your code surrounding APPNameCoreDataEvent.m line 35 doing? And what's APPNameCoreDataManager removeHistoryAnalytics: doing?

A stack trace and your header file aren't enough information to go on. You need to supply excerpts from the implemention file.

0

Answer 2

YIQ OP

Apr ’16

The surrounding APPNameCoreDataEvent.m:35 is the impelmentaion of model.

There is the code

- (APPNameCoreDataEvent *)model
{
    APPNameCoreDataEvent *model = [[APPNameCoreDataEvent alloc] init];
    for (NSString *key in [APPNameCoreDataEvent iterate_propertyNames]) {
        [model setValue:[self valueForKey:key] forKey:key];
    }
    return model;
}

While the impelmentation of removeHistoryAnalytics is below

- (void)removeHistoryAnalytics:(void (^)(APPAnalyticsHeader *header, NSSet *events))analytics
{
    [self.context performBlock:^{
        NSFetchRequest *fetchRequest = [NSFetchRequest fetchRequestWithEntityName:@"APPAnalyticsCoreDataHeader"];
        [fetchRequest setFetchBatchSize:3];
        NSArray *headers = [self.context executeFetchRequest:fetchRequest error:nil];
        for (APPAnalyticsCoreDataHeader *header in headers) {
            if ([header.objectID.URIRepresentation isEqual:_headerURL]) {
                continue;
            }
            NSMutableSet *events = [NSMutableSet setWithCapacity:header.events.count];
            for (APPNameCoreDataEvent *event in header.events) {
                [events addObject:event.model];
            }
            if (analytics) {
                analytics(header.model, events);
            }
            [self.context deleteObject:header];
        }
        NSError *error = nil;
        [self.context save:&error];
     }];
}

0

Answer 3

NotMyName OP

Apr ’16

(APPNameCoreDataEvent *)model
{
APPNameCoreDataEvent *model = [[APPNameCoreDataEvent alloc] init];
for (NSString *key in [APPNameCoreDataEvent iterate_propertyNames]) {
[model setValue:[self valueForKey:key] forKey:key];
}
return model;
}

If APPNameCoreDataEvent is a subclass of NSManagedObject, then the line [[APPNameCoreDataEvent alloc] init] and then set values on the object is part of the problem. In order to work properly, a Core Data object has to exist in a managed object context before you get and set attribute values on it.

Why are you trying to make copies of the managed objects like that?

0