Application crashes when executing NSBatchDeleteRequest with "Unknown command type <NSBatchDeleteRequest, ..>"

Question

I am writing an OS X application and it should be able to delete all instances of "SongEntity" stored in the master data store. However, when I try to execute NSBatchDeleteRequest, my application crashes with the following console output (excerpt):

Unknown command type (entity: SongEntity; predicate: ((zero)); sortDescriptors: ((null)); type: NSManagedObjectIDResultType;)>

Here is my implementation:

func clearStore() { let fetchRequest = NSFetchRequest(entityName: "SongEntity") let deleteRequest = NSBatchDeleteRequest(fetchRequest: fetchRequest) do { try managedObjectContext.executeRequest(deleteRequest) } catch { fatalError("Not able to perform operation: \(error)") } managedObjectContext.reset() } 

Any help would be greatly appreciated

EDIT: It turns out this problem is related to the selected storage type: From the NSBatchDeleteRequest class:

 // May not be supported by all store types. 

I tried changing the storage type from NSXMLStoreType (default macOS template) to NSSQLiteStoreType , and now it works.

Answer 1

NSBatchDeleteRequest is executed in the persistent storage coordinator, and not in the context of a managed entity.

 try persistentStoreCoordinator.executeFetchRequest( batchDeleteRequest, withContext:context )