Saving in child context saves to parent context automatically - ios

Question

I'm trying to create an update function that also allows the user to cancel the process.
I'm using the parent-child managedObjectContext and I've set the parent contest concurrency to NSMainQueueConcurrencyType. My plan was to not call the save for parent context to cancel the update. When I tested my theory and commented out the said save lines, I found out the managedObject was still updated. What am I doing wrong?
Partial update function code:
NSManagedObjectContext *bgContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSPrivateQueueConcurrencyType];
[bgContext setParentContext:self.managedObjectContext];
[bgContext setUndoManager:nil];
[bgContext performBlockAndWait:^{
for (NSDictionary *itemDictionary in items) {
//update cancelled
if (status == -1) {
return;
}
//Function to get a single managedObject by querying the main context.
NSArray *array = [self queryEntity:entityName withResId:[dictionary objectForKey:#"res_id"]];
//get the object id of queried managedobject; context -> mainContext
ENTITY *object = (ENTITY *)[context objectWithID:[[array firstObject] objectID]];
object.data = #"something"; //change data
count++;
//save every 100
if(count%100 == 0) {
[bgContext performBlockAndWait:^{
NSError *error;
if(![bgContext save:&error]) {
NSLog(#"insert error child: %#", [error localizedDescription]);
}
}];
}
}
//save excess
if(count%100 != 0) {
[bgContext performBlockAndWait:^{
NSError *error;
if(![bgContext save:&error]) {
NSLog(#"insert error child: %#", [error localizedDescription]);
}
}];
}
//comment out to prevent saving to parent
/*[context performBlockAndWait:^{
NSError *error;
if(![context save:&error]) {
NSLog(#"insert error parent: %#", [error localizedDescription]);
}
}];*/
}];

Answer 1

Found my problem. Thanks to this post: https://stackoverflow.com/a/7825536/2260928
I use these lines to ignore changes on cancel:
[bgContext reset];
[context reset];