Setter for NSManagedObject creates _CDSnapshot_Provence_

问题

I have two NSManagedObject:

DataEntered
Provence

There is a relation between them: DataEntered must have ONE Provence, and Provence may have one/multiple DataEntered.

All is working well, but when using Instruments and Allocations, every time I set the Provence to DataEntered, a new _CDSnapshot_Provence_ appears in #Living:

Provence * provence = [[self fetchedResultsController] objectAtIndexPath:indexPath];
[self.dataEntered setAddress_provence:provence];

The setter for Provence in DataEntered is managed by CoreData, there is no customization.

When I save DataEntered, is saved correctly. What can cause the creation of multiple living _CDSnapshot_Provence_ ?

Thanks!

@class Provence;

@interface DataEntered : NSManagedObject

@property (nonatomic, retain) NSString * name;
@property (nonatomic, strong) Provence *address_provence;

@end


@class Provence;

@interface DataEntered : NSManagedObject

@property (nonatomic, retain) NSString * name;
@property (nonatomic, strong) Provence *address_provence;

@end



@class DataEntered;

@interface Provence : NSManagedObject

@property (nonatomic, retain) NSString * name;
@property (nonatomic, retain) NSSet *dataEnteredAddress_Provence;

@end


@interface Provence (CoreDataGeneratedAccessors)

- (void)addDataEnteredAddress_ProvenceObject:(DataEntered *)value;
- (void)removeDataEnteredAddress_ProvenceObject:(DataEntered *)value;
- (void)addDataEnteredAddress_Provence:(NSSet *)values;
- (void)removeDataEnteredAddress_Provence:(NSSet *)values;

@end


#import "Provence.h"
#import "DataEntered.h"


@implementation Provence

@dynamic name;
@dynamic dataEnteredAddress_Provence;

@end

回答1:

I saw exactly the same thing and I believe that this is to be expected.

See the section Conflict Detection and Optimistic Locking in the Apple docs at https://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/CoreData/Articles/cdChangeManagement.html

"When Core Data fetches an object from a persistent store, it takes a snapshot of its state. A snapshot is a dictionary of an object’s persistent properties—typically all its attributes and the global IDs of any objects to which it has a to-one relationship."

There is also a section at that same link that is useful to read - Snapshot Management

The problem I ran into was getting Core Data to release its memory allocations after I had faulted all the managed objects or did a context reset.

I just published a blog posting on this and related topics: Core Data issues with memory allocation - http://finalize.com/2013/01/04/core-data-issues-with-memory-allocation/

Hope this helps.

Scott

来源：https://stackoverflow.com/questions/12979085/setter-for-nsmanagedobject-creates-cdsnapshot-provence

标签

ios

core-data

nsmanagedobject