Implementing UITableViewDataSource methods in TableViewDataSource #23

I wanted to implement swipe-to-delete in one of my UITableViewControllers. This VC displays a table of objects that inherit from ManagedObject and implement ManagedObjectType. To do so, the VC's dataSource needs to implement the tableView(tableView: commitEditingStyle: forRowAtIndexPath:) method, and handle the .Delete case. To delete I simply do the following:

In TableViewDataSource.swift

// MARK: UITableViewDataSource methods
    func tableView(tableView: UITableView, commitEditingStyle editingStyle: UITableViewCellEditingStyle, forRowAtIndexPath indexPath: NSIndexPath) {

        switch editingStyle {
        case .Delete:
            let deleted = dataProvider.objectAtIndexPath(indexPath) as! ManagedObject
            print("Deleted: \(deleted)")
            deleted.delete()

        default: break
        }
    }

delete() is simply:

In ManagedObject.swift

/// ManagedObject - protocol extension that implements defaults
extension ManagedObject {
    public func delete() {
        managedObjectContext?.performChanges({ 
            self.managedObjectContext?.deleteObject(self)
        })
    }
}

Because the TableViewDataSource does not have access to the NSManagedObjectContext, but the ManagedObject does, I am required to cast down to ManagedObject, as the TableViewDataSource's where clause does not actually require ManagedObject.

Is there a better way to handle this? Obviously, I would implement a guard in the cast, but I was wondering if there were a better way to implement deleting an object in this way? Without access to the moc, and without access to the tableView's delegate it seems I have to require some type constraints on the Object to be able to delete.

for reference, the TableViewDataSource generic requirements

class TableViewDataSource<Delegate: DataSourceDelegate, Data: DataProvider, Cell: UITableViewCell where Delegate.Object == Data.Object, Cell: ConfigurableCell, Cell.DataSource == Data.Object>: NSObject, UITableViewDataSource