Question

Thanks for the help.

Core Data project. I’m importing text from a text file and I want to display it in an NSTextView whose value binding I have bound to the arrayController’s selection with model key path text. The array controller contains instances of my entity, which has a string attribute named text. I want to update the arrayController for the key value bound to the textView so it can be saved. No errors when building, but not working. How do I do this?

id newObject = [arrayController newObject];

[arrayController addObject:newObject forKey:@"text"];

[newObject release];

Answer 1

[arrayController addObject:newObject forKey:@"text"];

This is “not working” because an NSArrayController doesn’t respond to such a message. An array controller controls an array, not a key-value mapping; it does not have keys you can add objects for.

That, in turn, is because “array” in Cocoa means an ordered consecutive list, not an associative array. Cocoa calls a key-value mapping/associative array a “dictionary”.

The model key path is exactly that: The key path into the model of the property you want to bind the text view to. You seem to already know this; I assume you entered text here because it’s what you named the attribute in your model. Your binding is correct.

But this also means that “text” has nothing to do with the array controller. It is a property of the model entities, not the controller. You need to set that property of the model object—in this case, newObject—not in the controller.