NSConstraintConflict
An encapsulation of conflicts that occur during an attempt to save a managed object.
Declaration
class NSConstraintConflictOverview
A constraint conflict occurs when your data model is using unique constraints and one or more managed objects are violating that constraint.
When this error occurs, the error instance can be interrogated to determine which instance of NSManagedObject is violating the constraint and which property on the NSManagedObject instance is in violation.