Save a large number of objects in coredata - ios

Question

I try to save many objects in coredata, but get this crash:
Communications error: <OS_xpc_error: <error: 0x19b354af0> { count = 1, contents =
"XPCErrorDescription" => <string: 0x19b354e50> { length = 22, contents = "Connection interrupted" }
}>
Message from debugger: Terminated due to memory issue
I use MagicalRecord:
[MagicalRecord saveInBackgroundWithBlock:^(NSManagedObjectContext *localContext){
for (int i = 0; i < json.count; i++) {
[Product parseWithData:((NSMutableArray *)json)[i]];
}
}];
Product.m
+ (void)parseWithData:(NSDictionary *)dictionary {
NSString *xml_id = [dictionary[#"XML_ID"] isKindOfClass:[NSString class]] ? dictionary[#"XML_ID"] : #"";
Product *product = [Product getProductWithXML_id:xml_id];
if (!product)
product = [Product MR_createEntity];
product.xml_id = xml_id;
product.code = [dictionary[#"Code"] isKindOfClass:[NSString class]] ? dictionary[#"Code"] : #"";
...
}
Can you suggest me, how can i save it?
When i save my objects in loop to core data - memory grow very fast

Answer 1

It seems to be a memory issue.
Try surrounding the inner part of your for loop with
autoreleasepool {
...
}

Answer 2

You need to paginate the way you get the data and/or save it.
By paginate, i mean :
download the first 1000 (for example, it depends on the content really)
When its done, save the 1000 you just go
When that is done, get the next 1000, save it again, and so on.
You need to know the number you're trying to get and use the (if I remember correctly ) SetLimit: on the parse method, and SetSkip. The skip skips the X first elements, and the limit is the max number of items that will be downloaded.
That way, you skip 0 with limit 1000, then recall the method with skip += limit, and you'll get the second 1000 chunk, and so on. The last chunk will obviously be smaller than 1000.
Doing this will drastically increase the time taken, but that could be done seamlessly in the background ; but it will be spread over much enough to need less memory.
Do it, and see if it makes a big difference. If not, you could always reduce to 500 instead of 1000, or completely change your architecture ; maybe you don't even need ALL the items right now !