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Answer 1

+4 A:

It seems to me that storing images in a core data isn't a good idea, and I'm pretty sure I've also read it on one of Apple's programming guides. Just consider this, when you fetch your collection, all the images will also be loaded into memory, even if you're only displaying 8 images, your entire image collection will be loaded by core data.

If you want to make sure you delete the image files when a move record was deleted I suggest you listen to notifications by the managedObjectContext and delete files when a movie was deleted:

You can either register for the willSave or didSave notification, each with it's own advantages/disadvantages.

    [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(contextDidSave:) name:NSManagedObjectContextDidSaveNotification object:managedObjectContext];

Getting the deleted objects:

- (void) contextDidSave:(NSNotification *)notification
{
    NSDictionary *userInfo = [notification userInfo];
    for (NSManagedObject *currObject in [userInfo objectForKey:NSDeletedObjectsKey])
    {
         // Code for deleting file associated with the NSManagedObject, you can still
         // access the managed object's properties.
    }
}

Ron Srebro 2010-01-25 11:23:21

There is nothing wrong with storing binary data in Core Data, especially of the image sizes that the OP is working with. Review the two links posted as a note to the question. Anything under 100KB can easily be stored directly in Core Data.

Marcus S. Zarra 2010-01-27 08:19:52

Of course it can be done, but in my opinion is just not the best way to do it, unless you can control if the binary data is actually fetched and loaded to memory. Otherwise fetching a 100 records will load 2/3mb into memory for no reason at all.

Ron Srebro 2010-01-27 10:57:22

Answer 2

A:

It occurred to me that you can use another approach which might be better if you're already subclassing NSManagedObject for your movie entity.

You can implement the didSave or willSave method on the NSManagedObject and check isDeleted property. If it is deleted, delete the image from disk.

Ron Srebro 2010-01-25 11:32:22

Answer 3

+2 A:

The best method is to store the path to the image in the managed object and then delete the file in the object's prepareForDeletion method.

TechZen 2010-01-25 14:07:17

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CoreData (for iphone) storing images

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