Delete Rules of Core data

Core Data Delete Rules:

1. No Action :
    When source is deleted, but destination won't be notified.

2. Nullify : [It is default one by core data]
    When source is deleted, but the relationship is nullified, won't effect on destination.

3. Cascade : [Not safe]
    When source is deleted, and it also sent to delete the destination as well
    by cascading info to destination.

4. Deny : [Kind of Safe Check]
    When source is deleted, the destinations won't get any effect.
    And The source will be deleted until and unless its associated

    all destinations will be deleted.
    So it will deny if associated destination still exist.