Hi László Harri,

Thank you for your clear & simple code example. It enables me to learn CoreData concept easier.

However, I do have some suggestion on the sample code.

I notice you are using the following code, to "return back" to MasterViewController from ReallySimpleNoteCreateChangeViewController

    // navigate back to list of notes
    performSegue(
        withIdentifier: "backToMasterView",
        sender: self
    )

However, by doing so, a new MasterViewController will be created each time, with old MasterViewController still remain in memory stack. This can be confirmed, by adding some debug message in MasterViewController's init and deinit

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        print("MasterViewController init")
    }
    
    deinit {
        print("MasterViewController's deinit")
    }

We will observe that init being called multiple times, and deinit never being called. Very soon. Out of memory may occur. I guess, we should use an unwind segue.

For

private var noteIndexToIdDict : [Int:UUID] = [:]

May I suggest that using

private var noteIds : [UUID] = []

We may use the Int index to perform direct array access.

I appreciate your tutorial and code sample. It enables me to kick start learning Core Data with less pressure.