NSTableView & CoreData: Delete Object at clicked row

Question

I am pretty new to Core Data and am currently working on a small (OSX) app that uses an NSTableView to organise objects. I would now like to delete a row/object with the click of a button on that targeted row.

I access the managed object within the table controller by calling [NSApp managedObjectContext] (still trying to figure out that dependency injection thing) but I can't easily delete an objectAtIndex: like I used to with the array (which has now been replaced by the core data stack, right?).

How do I identify the object to be deleted? And consequently, how can I cleanly remove it from the stack?

This is probably a really basic question but I couldn't find any resources on it. Bindings obviously don't work because the row does not get selected before the click occurs.

Any help is much appreciated!

Answer 1

Bindings would work, in that you could have the button's IBAction query the objectValue for the parent NSTableCellView. Once you have that objectValue, you could call the bound arrayController to delete the object, and then the cell/row would disappear.

So, if you have a tableCellView that has a delete button with an IBAction, within that IBAction, you could get the sender's superview, ensure it's an NSTableCellView, get the objectValue, and call [myArrayController removeObject:...]

As it says in the NSTableCellView class reference:

The objectValue is automatically set by the table when using bindings or is the object returned by the NSTableViewDataSource protocol method tableView:objectValueForTableColumn:row:.

This is actually a typical pattern with views in cocoa. objectValue or often representedObject are properties on the views that refer to the data model objects they represent, so if you have a view pointer from sender on the IBAction, you can get the related data model object. And if you're using bindings and a controller, you can then just have the controller remove that object.

With bindings, you will often create buttons that need IBActions attached, rather than some direct binding. But those IBActions can most definitely interact with the controller and not the view.

And with core data, array controllers are really slick vs. assuming you have to do it all programmatically.