What you are doing is NOT thread safe.
If you decide to create a context per operation, you better use the confinement concurrency type:
context = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSConfinementConcurrencyType];
this way you don't need to change anything in your current code.
if you want to use the context with NSPrivateQueueConcurrencyType
you must access objects within that context by the performBlock:
or performBlockAndWait:
:
[managedObjectContext performBlockAndWait:^{//wait is used as to not end the operation before this code is executed
for (NSDictionary *articleDictionary in array) {
if (![Article articleExistsWithIDInDictionary:articleDictionary
inContext:managedObjectContext])
{
[Article articleFromDictionary:articleDictionary
inContext:managedObjectContext];
}
}
}];
I would probably go with my first solution in your case.
all that said, you could simply use a "private queue" context as a serial queue (as long as you add block operation to it in the order you need them to execute).
A context performBlock:
method will queue the block and execute it serially in regard to other blocks added that context for execution in the background:
//add this to your CoreDataController
context = [[CoreDataController sharedCoreDataController] serialExecutionBGContext];
[context performBlock:^{ //your block operation code1}];
[context performBlock:^{ //your block operation code2}];
this will perform code1 and code2 in the background serially.
In this manner, you save the overhead of allocating a new context, and might benefit from caching done by this context.
You might want to reset this context every now and then so it will not get bloated with fetched objects.