How to insert batch data with CoreData? - ios

Question

My situation is more than 200 objects would come to me one by one per second through a callback function, obviously I cannot save a entity every single time in this callback function, that will cause UI suspend, so my question is how to insert batch data with core data?
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Edit:
thanks, guys, I re-edit my code like this, and there are some issues,
if I receive "1", "2", "3"...from the callback function frequently, my tableview often shows "1", "3", "2"... , they are in wrong order. if anything wrong, plz let me know.
in AppDelegate.m file:
- (NSManagedObjectContext *)mainManagedObjectContext {
if (_ mainManagedObjectContext != nil) {
return _managedObjectContext;
}
_mainManagedObjectContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];
_mainManagedObjectContext.parentContext = [self rootManagedObjectContext];
return _mainManagedObjectContext;
}
- (NSManagedObjectContext*)rootManagedObjectContext {
if (_rootManagedObjectContext != nil) {
return _rootManagedObjectContext;
}
NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];
if (!coordinator) {
return nil;
}
_rootManagedObjectContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSPrivateQueueConcurrencyType];
[_rootManagedObjectContext setPersistentStoreCoordinator:coordinator];
return _rootManagedObjectContext;
}
in the callback function I do this, I tried to replace _mainManagedObjectContext
with _rootContext or _workContextint callback function, but data never show on the tableview;
- (void)saveChatMessage:(ChatMessage*)msg userInfo:(UserInfo*)user chatType:(ChatType)chatType receiverID:(long long)receiverID receiverName:(NSString*)receiverName
{
ChatObject *chatObject = [NSEntityDescription
insertNewObjectForEntityForName:#"ChatObject"
inManagedObjectContext: _mainManagedObjectContext];
chatObject.receiveTime = [NSNumber numberWithLongLong:[NSDate date].timeIntervalSince1970];
chatObject.text = msg.text;
chatObject.richText = msg.richText;
chatObject.senderID = [NSNumber numberWithLongLong:user.userID];
chatObject.senderName = user.userName;
chatObject.chatType = [NSNumber numberWithInteger:chatType];
chatObject.isFromHost = [NSNumber numberWithBool:user.isOrganizer];
chatObject.receiverID = [NSNumber numberWithLongLong:receiverID];
chatObject.receiverName = receiverName;
NSError *error;
if (![_workerContext save:&error]) {
}
if (![_rootContext save:&error]) {
}
}
- (NSFetchedResultsController *)fetchedResultsController {
if (_fetchedResultsController != nil) {
return _fetchedResultsController;
}
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
NSEntityDescription *entity = [NSEntityDescription
entityForName:#"ChatObject" inManagedObjectContext:_mainManagedObjectContext];
[fetchRequest setEntity:entity];
NSSortDescriptor *sort = [[NSSortDescriptor alloc]
initWithKey:#"receiveTime" ascending:YES];
[fetchRequest setSortDescriptors:[NSArray arrayWithObject:sort]];
[fetchRequest setFetchBatchSize:20];
NSFetchedResultsController *theFetchedResultsController =
[[NSFetchedResultsController alloc] initWithFetchRequest:fetchRequest
managedObjectContext:_mainManagedObjectContext sectionNameKeyPath:nil
cacheName:#"Root"];
self.fetchedResultsController = theFetchedResultsController;
_fetchedResultsController.delegate = self;
return _fetchedResultsController;
}

Answer 1

You have to use background contexts. I recommend this setup:
RootContext (background) for saving --> is parent of
MainContext (main thread) for UI --> is parent of
WorkerContext (background) for insert, update, delete operations
Root context and main context should be set up at app start. You can create a worker context in your web callbacks (when you have the new data available) and then use the context with the block APIs:
workerContext.performBlock() {
// update data here
}
When you call save() on the worker context, the UI context gets the changes and can update itself gracefully (e.g. via NSFetchedResultsControllerDelegate). Make sure you also call save on the root context to persist the data to the persistent store.
This is the basic outline of a good approach. In case you are not familiar with some of the mentioned techniques, you can find good and detailed explanations of many of these on this platform.

Answer 2

You can insert all data in a background thread and save the context when you are done - that will update the context in other threads. Just take care that all saving is done on that background thread to avoid concurrency problems.