Swift 3 Core Data Delete Object for Key

I am working on an app written in Swift that uses Core Data. For it to work correctly, I need to delete all the objects in Core Data for a specific entity and key. I have been able to find many different questions covering deleting from core data, but as far as I can tell none of them only delete objects for a specific key.

My current code follows a similar style to the "Fetch, Delete, Repeat" method in this article. It talks about an iOS 9 updated way to do this with NSBatchDeleteRequest, but I have not discovered any way to make either of these only delete the values for a specific key.

Current Delete Code (I have tried to add a key to the object, but it throws an error about not being able to cast NSCFNumber to NSManagedObject at runtime)

getContext().delete(object.value(forKey: key) as! NSManagedObject)

Full Code Pertaining to Core Data

func getContext () -> NSManagedObjectContext {
    let appDelegate = UIApplication.shared.delegate as! AppDelegate
    return appDelegate.persistentContainer.viewContext
}

func coreDataReplaceValue(entity: String, key: String, value: Int) {
    let fetchRequest:NSFetchRequest<NSFetchRequestResult> = NSFetchRequest(entityName: entity)

    do {
        let searchResults = try getContext().fetch(fetchRequest)

        for object in searchResults as! [NSManagedObject] {
            getContext().delete(object.value(forKey: key) as! NSManagedObject)
        }
    } catch {
        print("Error with request: \(error)")
    }


    let context = getContext()

    let entity =  NSEntityDescription.entity(forEntityName: entity, in: context)

    let accelerationLevel = NSManagedObject(entity: entity!, insertInto: context)

    accelerationLevel.setValue(value, forKey: key)

    do {
        try context.save()
        print("saved!")
    } catch let error as NSError  {
        print("Could not save \(error), \(error.userInfo)")
    } catch {

    }
}

Other questions I have looked at that pertain to my question, but don't include a way to add a key:

Swift 3 Core Data Delete Object

delete core data managed object with Swift 3

This last one looked promising at first, but the code changes it into an NSManagedObject, so I don't think it holds the solution.

Deleting first object in Core Data (Swift)

Thanks for any help!

Taylor