title: Correct time to delete persistent store to delete all entries of an entity
body: <p>I am using an UITableViewController containing a UITableView and an UISearchTableView.
  The table lists e.g. 1000 entries. I want to provide the user a button to delete all 
  entries of a specific entity. Because looping over all managed objects and saving the context takes a very long time, I thought of deleting by removing the persistent store and rebuilding the stack.</p>
  
  <p>Now to my questions: How can I do this in the UITableViewController? I don't want to restart the app for deletion so I want to move the code from the app delegate.</p>