Casting from 'NSPersistentStoreResult' to unrelated type 'Entity' always fails

I am creating a small app to learn the many to many relationships in CoreData. However using the code below I get an error casting from my NSFetchResult to my Entity class ('Groepering'):

I do not see any difference from samples I found on the internet compared to my project, why does the cast still fail?

let appDelegate = UIApplication.sharedApplication().delegate as! AppDelegate
let managedContext = appDelegate.managedObjectContext

let fetchRequest : NSFetchRequest = NSFetchRequest(entityName: "Entity")

    do {
        let fetchResults = try managedContext.executeRequest(fetchRequest)
        let groeperingen = fetchResults as! [Entity]
        // Here I get the Error: ^

    } catch {
        print("Error")
}

Use executeFetchRequest method of NSManagedObjectContext when performing a NSFetchRequest.

Edit Swift 3: For Swift 3, use:

let result = try managedContext.fetch(fetchRequest)

I recently converted my code to Swift 3 and ran into this same error, though not because of a typo. It seems that the new, equivalent function call is let fetchResults = try managedContext.fetch(fetchRequest).