Disposing of NSManagedObjectContexts in a Core Data management class

Question

So I am making a framework to hold all the code used to manipulate a core data database. What I have ended up having an issue with is this.

I have a method which returns a new item

- (NSManagedObject *)createItem;

once they have modified that item the would call

- (void)save;

This has to be able to be executed in multiple threads so the managed object I return from my method has to have an NSManagedObjectContext consistent inside a thread. My solution to solve this was to create a NSMutableDictionary to hold a references to NSManagedObjectContexts using

[NSThread hash]

as the key. This works great. The only problem is that I cannot get rid of the contexts once their threads have finished.

Does anyone have any idea on how I could detect that?

Here is the code for my managed object context method

// Return Managed Object Context for Framework
- (NSManagedObjectContext *)managedObjectContext
{
    // Get Thread Hash Value
    NSThread * currentThread = [NSThread currentThread];
    NSNumber * hashValue = [NSNumber numberWithUnsignedInteger:[currentThread hash]];

    // Get Context From Thread Hash
    NSManagedObjectContext * context = [self.managedObjectContexts objectForKey:hashValue];

    // Check Context Exists
    if (!context)
    {
        // Create Managed Object Context With Persistent Store Coordinator In Main Thread
        NSPersistentStoreCoordinator * coordinator = [self persistentStoreCoordinator];
        if (coordinator != nil) {
            context = [[NSManagedObjectContext alloc] init];
            [context setPersistentStoreCoordinator:coordinator];
        }

        // Add Context To Available Contexts
        [self.managedObjectContexts setObject:context forKey:hashValue];
    }

    // Return
    return context;
}

Answer 1

Look at using the threadDictionary available on each NSThread. In this way you can easily get the MOC for a thread (or know if there isn't one) and the cleanup will be handled for you.