Question

Suppose I have core data entities A and B, where B points to A via attribute a.

Given the NSEntityDescription for B, and a key path to a given property of A (e.g @”a.name”), is there any way to recover the NSEntityDescription of A?

Thanks,

Tim

Answer 1

I’ve managed to to this by parsing the key path myself:

    // Split the path to the section name up
    NSArray *keyNameParts = [sectionNameKeyPath componentsSeparatedByString:@"."];

    // Follow this back to the Entity description for the Section Entity
    for (int idx = 0; idx < keyNameParts.count - 1; idx++) {
        NSDictionary *relationships = entityDescription.relationshipsByName;
        NSString *partName = [keyNameParts objectAtIndex:idx];
        NSRelationshipDescription *relationshipDescription = [relationships objectForKey:partName];
        if (!relationshipDescription)
        {
            [NSException raise:@"Relationship not found for keypath"
                        format:@"Entity '%@' does not point to a relationshop for '%@' in keypath '@'.", entityName, partName, sectionNameKeyPath];
        }
        entityDescription = relationshipDescription.entity;
    } 

If there’s a more direct method I’d love to know it.