title: How to clear all objects in NSManagedObjectContext?
body: <p>It is okay to add or delete single object in NSManagedObjectContext,just wonder why there is no API to clear all objects one time in NSManagedObjectContext ?</p>
  
  <blockquote>
    <p>Specifies an object that should be removed from its persistent store when changes are committed.</p>
    
    <ul>
    <li>(void)deleteObject:(NSManagedObject *)object</li>
    </ul>
  </blockquote>
  
  <p>Why there is no API such as clearAllObjects to delete all objects at one time ?</p>