Core data queue confinement

gistfile1.m

///Somewhere in application startup, where you setup a core data stack
NSOperationQueue *coreDataSerialOperationQueue;
coreDataSerialOperationQueue = [[NSOperationQueue alloc] init];
[coreDataSerialOperationQueue setMaxConcurrentOperationCount:1];


///All core data operations should be wrapped in this method for safety
+ (RCOperation *) addCoreDataOperation:(void (^)(void))coreDataOperation
{
    NSAssert(coreDataSerialOperationQueue,@"coreDataSerialOperationQueue was nil");
    NSParameterAssert(coreDataOperation);
    NSOperation *operation = [[NSOperation alloc] init];
    [operation addExecutionBlock:coreDataOperation];
    [coreDataSerialOperationQueue addOperation:operation];
    return operation;
}

///Usage somewhere in a UI callback
NSManagedObjectContext *context = comment.managedObjectContext;
[RCCoreData addCoreDataOperation:^{

    //Note: wait for completion in the context of this operation
    [context performBlockAndWait:^{
        [comment setAPIVote:vote];
        
        NSError *error;
        [context save:&error];
        
        //Handle error
        
        //And if the save needs to be propagated to a persistent store
        [context.parentContext save:&error];
        
        //Handle error
    }];
}];