how can I remove all objects? I know I can remove one by
[managedObjectContext deleteObject:objToDelete];
is it possible to delete all wit
You can also just tear down the stack (releasing the NSManagedObjectContext, NSPersistentStore and NSManagedObjectModel) and delete the file. Probably would be faster than iterating over your entire database and deleting each object individually.
Also, it is unlikely they will provide this functionality in the future because it is easy to delete the file. However if you feel it is important then file a radar and let Apple know. Otherwise they won't know how many people want this feature.