NSManagedObjectID into NSData

Question

I found this wonderful NSManagedObjectID. This would be very good for referencing an Entity/NSManagedObject/NSEntityDescription, right?
Let\'s get an ID from an entity:<

Answer 1

Here's the cleanest and shortest way I've found to do this currently, using the setURL and getURL methods added in 4.0 to avoid extra calls to NSKeyedUnarchiver and NSKeyedArchiver:

Setter:

 + (void)storeSomeObjectId:(NSManagedObjectID *)objectId
 {
     [[NSUserDefaults standardUserDefaults] setURL:[objectId URIRepresentation] 
                                            forKey:@"someObjectIdKey"];
     [[NSUserDefaults standardUserDefaults] synchronize];
 }

Getter:

 + (SomeManagedObject *)getObjectByStoredId
 {
     NSURL *uri = [[NSUserDefaults standardUserDefaults] URLForKey:@"someObjectIdKey"];
     NSManagedObjectID *objectId = [self.persistentStoreCoordinator managedObjectIDForURIRepresentation:uri];
     SomeManagedObject *object = [self.managedObjectContext objectWithID:objectId];
 }