Core Data - removing items

Question

I have a question due to some doubts about some of my code. In an array of NSManagedObject I need to get rid of some of them. Here is (below) the code I use. I have to say it works, within my range of experience. So my question is more to make sure I am not doing something wrong rather than to solve an existing problem

for (NSManagedObject *item in objects) {
    if ([[item valueForKey:@"OK"] intValue]>1) {
        [context deleteObject:item];
        continue;
    }
}

Since I am modifying the content of the array "objects" while looping on it, I fear that my code is kind of unsafe. Of course it all depends on how things are handled behind the scene, which I do not know.

Thanks.

Answer 1

When you call deleteObject: you are flagging an object for deletion, not deleting it immediately, and certainly not deleting it from the collection that you are iterating during the iteration.

From the docs:

Specifies an object that should be removed from its persistent store when changes are committed.

If you inspect the deleted items after the deleteObject: call you will see the objects still exist but have their isDeleted flags set to YES. The object will actually be deleted when the NSManagedObjectContext is next saved.

Answer 2

You are only flagging the item for deletion with your deleteObject line. In order to force the context to execute the deletion, run this at the bottom of your function:

NSError *error;
if (![context save:&error]) {
    return;
}