I've been working on incorporating AFIncrementalStore into our app following the example code in the repository that uses an SQLite backing store. All the examples use a singleton managedObjectContext with an NSMainQueueConcurrencyType.
+ (NSManagedObjectContext *)managedObjectContext {
static NSManagedObjectContext *_managedObjectContext = nil;
static dispatch_once_t onceToken;
dispatch_once(&onceToken, ^{
NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];
if (coordinator != nil) {
_managedObjectContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];
[_managedObjectContext setPersistentStoreCoordinator:coordinator];
}
});
return _managedObjectContext;
}
Using this moc, I'm able to perform a fetch, see it get pulled from the network, and stored in the sqlite backing store. I tried changing it to use the NSPrivateQueueConcurrencyType, and while I would see the network request, nothing was ever saved to the SQLite backing store. However, if I leave this moc with main queue concurrency, and then create a child from it, and use that moc, then everything saves fine.
+ (User *)user
{
// grab a user if we already have one
NSManagedObjectContext *managedObjectContext = [VigilCoreDatabase managedObjectContext];
NSManagedObjectContext *tmpContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSPrivateQueueConcurrencyType];
tmpContext.parentContext = managedObjectContext;
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
fetchRequest.fetchLimit = 1;
[fetchRequest setAffectedStores:@[ ]];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"User" inManagedObjectContext:tmpContext];
[fetchRequest setEntity:entity];
__block User *user = nil;
[tmpContext performBlockAndWait:^{
NSError *error = nil;
NSArray *fetchedObjects = [tmpContext executeFetchRequest:fetchRequest error:&error];
if (fetchedObjects == nil) {
NSLog(@"error");
}
if(fetchedObjects.count > 0) {
user = fetchedObjects[0];
}
}];
return user;
}
I wanted to figure out if I was missing something in my understanding. I can't seem to find any examples that don't use a moc with main queue concurrency as the parent context (with the backing store using a private queue context), but at the same time can't find any documentation explaining whether this is required, or whether I need to do something to push changes to the parent manually when using a private queue context vs. having a main queue context in the stack.
