Error saving data in Core Data (IOS) - ios

Question

My program receives the JSON data from the Web service. Next, the program stores the data in the database using Core Data. If I call the save data after adding each entry, everything works, but very slowly. Keeping 200 entries takes more than one minute.
If I execute saving only once at the end – the program throw exception.
- (void) onLoadMessages:(NSObject*)object {
NSArray *messages = (NSArray*)object;
if (messages==nil) {
[self onError:#"Message array is null"];
return;
}
NSDate *date = [NSDate date];
long now = [date timeIntervalSince1970];
Boolean update = false;
for(int i=0; i<messages.count; i++) {
NSDictionary *m = messages[i];
Message *msg = [[Message alloc]initWithDictionary:m];
if ([self UpdateMessage:msg UpdateTime:now])
update = true;
}
if (update) {
NSError *error = nil;
// Error throw here
if (![self.managedObjectContext save:&error])
[self onError2:error];
}
}
- (Boolean) UpdateMessage:(Message*) msg UpdateTime:(long)now {
NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
// Edit the entity name as appropriate.
NSEntityDescription *entity = [NSEntityDescription entityForName:#"Messages" inManagedObjectContext:self.managedObjectContext];
[fetchRequest setEntity:entity];
NSString *s = [NSString stringWithFormat:#"%ld", msg.id];
NSPredicate *pred = [NSPredicate predicateWithFormat:#"(id=%#)", s];
[fetchRequest setPredicate:pred];
NSError *error;
NSArray *object = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error];
Boolean result = false;
if (object==nil)
[self onError2:error];
else {
NSManagedObject *m;
if ([object count]==0) {
// Insert new message
m = [NSEntityDescription insertNewObjectForEntityForName:#"Messages"
inManagedObjectContext:self.managedObjectContext];
[m setValue:[NSNumber numberWithLong:msg.id] forKey:#"id"];
[m setValue:[NSNumber numberWithLong:msg.agancy.id] forKey:#"agancy"];
[m setValue:msg.header forKey:#"header"];
[m setValue:msg.keywords forKey:#"keywords"];
[m setValue:[NSNumber numberWithLong:msg.indate] forKey:#"indate"];
[m setValue:[NSNumber numberWithLong:now] forKey:#"updated"];
result = true;
} else {
// Update message
m = [object objectAtIndex:0];
[m setValue:[NSNumber numberWithLong:now] forKey:#"updated"];
}
// Save the context.
// Too long execution
/*NSError *error = nil;
if (![self.managedObjectContext save:&error])
[self onError2:error];*/
}
return result;
}
Help correct the behavior of the program.
With respect,
Alexander.
P.S.
Execution takes place in the main thread.
Field "Id" for table "Messages" indexed.

Answer 1

I solve the problem by adding privateObjectContext!
_privateObjectContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSPrivateQueueConcurrencyType];
And replace managedObjectContext on privateObjectContext when updating/inserting data/