Is there any way we can restrict duplicate entries in core data?

Question

I have been trying to add objects in core data. So, i want that it should not allow duplicate entries in core data store. How to do that? This is my code related to save data.

Answer 1

Let me put the best approach from Apple Sample code itself. Please refer the sample code "ThreadedCoreData" for more info.

https://developer.apple.com/library/content/samplecode/ThreadedCoreData/Introduction/Intro.html

    // before adding the earthquake, first check if there's a duplicate in the backing store
    NSError *error = nil;
    Earthquake *earthquake = nil;
    for (earthquake in earthquakes) {
        fetchRequest.predicate = [NSPredicate predicateWithFormat:@"location = %@ AND date = %@", earthquake.location, earthquake.date];

        NSArray *fetchedItems = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error];
        if (fetchedItems.count == 0) {
            // we found no duplicate earthquakes, so insert this new one
            [self.managedObjectContext insertObject:earthquake];
        }
    }