Managed object: efficiently delete duplicates?

[msf5042]

I have an app that loops through an XML file and creates a managed object from the attributes. The app does this every time it starts. The XML file is large so efficiency is important. One of the attributes for an object is "QID". I need to figure out the best way to avoid multiple objects of the same QID. As it is now, I am looping through the XML attributes and when I get to the QID attribute I do a fetch request to see if it already exists, and if it does then I delete the object and continue. This takes forever because the fetch is happening a few hundred times. What is a good way to handle this? Any suggestions are appreciated. I am not a noob nor a jedi with Obj-C. A code snippet showing what I am doing is below.

for(NSDictionary *d in query) {
	if([(NSString *)[d valueForKey:@"nodeName"] isEqualToString:@"Q"]) {
		Question *q = (Question *)[NSEntityDescription 
			insertNewObjectForEntityForName:@"Question" 
			inManagedObjectContext:managedObjectContext];
		for(NSDictionary *d in (NSArray *)[d objectForKey:@"nodeChildArray"]) {
			[q setValue:[d valueForKey:@"nodeContent"] 
				forKey:[d valueForKey:@"nodeName"]];
		}
		NSFetchRequest *request = [[NSFetchRequest alloc] init];
		NSEntityDescription *entity = [NSEntityDescription 
			entityForName:@"Question" 
			inManagedObjectContext:managedObjectContext];
		NSPredicate *predicate = [NSPredicate 
			predicateWithFormat:@"(QID = %@)", q.QID];
		[request setEntity:entity];
		[request setPredicate:predicate];
		NSArray *array = [managedObjectContext 
			executeFetchRequest:request error:&error];
		if (array != nil && [array count] > 0)
		{
			for(Question *q2 in array) {
				if(![q2 isEqual:q]) {
					[managedObjectContext deleteObject:q2];
				}
			}
		}
}

[Stubborn Dreams]

The app does this every time it starts.

Bad data/incorrect data is a pain... However, processing to eliminate duplicates manually every time on app startup does not seem right to me.

Is this XML file shipped with the app or is it dynamic (downloaded from the web)?

If the XML file is dynamic (from the web), as always, I would greatly prefer processing the XML file using a server-side script to remove duplicates, as this offloads processing that would be needlessly duplicated across devices.

If the XML file is not dynamic and the data does not change, you should ship a CoreData database (ideally sqlite) with your app.

If the XML file is not dynamic and the data does change, you should ship a CoreData database with the entities that do not change separated (if possible) from the entities that do change.