CoreDataObjectInsertionAndEditing

[ Page re-factored to be a how-to. ]

Often times developers have the need to immediately edit an attribute (such as a title) of a newly-inserted object in a table. For instance, inserting a new “entry” into a list of entries, you’ll want to immediately begin editing the title rather than naming it “New Entry” and forcing the user to double-click to edit the title, since that’s the first thing users are likely to want to do. There are several key things to keep in mind when doing this with a CoreData application using the CocoaBindings mechanism.

Insertion

After the new entity instance is inserted into the managed object context (either via an object controller’s -add: method or by NSEntityDescription’s +insertNewObjectForEntityForName:inManagedObjectContext: method), you should make any changes to the object, then call your managed object context’s -processPendingChanges method.

(IBAction)newEntry:(id)sender { // Add a new entry id newEntry = [NSEntityDescription insertNewObjectForEntityForName:@”Entry” inManagedObjectContext:[self managedObjectContext]]; // Make changes to newEntry here …
```
 // Force the context to process the changes   self managedObjectContext] processPendingChanges];

 // Inform some controller that it needs
 // to rename the entry   if (newEntry)
  [someController renameEntry:newEntry]; }
```

Select & Edit New Object’s Property

The next step is to get the index of the newly-inserted object from the array controller, select it, then edit it. (The example below assumes entryTitleColumn is of course a valid reference to our title column.) Since the array controller manages the table view’s selection, you need to adjust the array controller’s selection before attempting to edit the column/row or (due to timing issues), the request to edit will sporadically fail due to the array controller insisting on its own selection indices. That’s the trick I was missing. :-)

(void)renameEntry:(id)entry { // Get the column index for our title column int col = [[entryTableView tableColumns] indexOfObject:entryTitleColumn];

 // Get the entry's index in the array controller's arranged objects   int row = [[entryArrayController arrangedObjects] indexOfObject:entry];

 // Set the array controller's selection   [entryArrayController setSelectionIndex:row];

 // Begin editing for the table view   [entryTableView editColumn:col row:row withEvent:nil select:YES]; }

It’s brain-dead simple once you know how … Of course you could combine these two methods into one, but in my case, the editing was happening in a separate nib and the renaming code is to be reused, so I separated the two.

Discussion

*[[NSArrayController - neitha' an array noa' a controlla' ... discuss.</Mike Myers jewish princess voice>*

FYI: Corrected code int row = entryArrayController arrangedObjects] indexOfObject:entry]; (right?) –[[CharlesParnot

Right. My bad. Thanks, again, Charles.

Now how does this work with an NSTreeController and NSOutlineView? NSTreeController does not understand setSelectionIndex: but rather requires an NSIndexPath via setSelectionIndexPath:. How do you determine the index path to a given object as above?

CocoaDev