How is NSTableView Content Sorted After Array Controller Add? - cocoa

Question

After adding a managed object in array controller class, the bound table view 'places' it into the correct date sorted order.
However, as the table view is building it's rows, the new object has been placed at the bottom of the array controller's content array using:
Edit: Solution: Don't use the array controller's content. The issue was in:
- (NSView *)tableView:(NSTableView *)tableView viewForTableColumn:(NSTableColumn *)tableColumn row:(NSInteger)row {
....
// originally
NSManagedObject *ci = [[self.arrayController content] objectAtIndex:row];
// should be: (note arrangedObjects replacing content)
NSManagedObject *ci = [self.arrayController.arrangedObjects objectAtIndex:row];
....
}
The image below shows an example of the placement. Console output from within -tableView: viewForTableColumn: row: at left (from original code above) and ordering in the table view on right. LHR is the new object (notice date order ascending).
Tried:
Saving the moc right after adding newObject
Calling Array Controller's arrangeObjects method
Attempting to manually setSortDescriptors
Binding the table view's selection index to the array controller (for grins)
This is also messing up the selectedRow even though the row with LHR is selected in the table view right after adding. The only way to correct the array controller's order is to manually sort the column.
How can the array controller's content be in sync with the table view? Even more, why might they not be in the same order?

Answer 1

The array controller "arranges" its content. It does this by calling its -arrangeObjects: method. The default implementation filters the contents using the array controller's filterPredicate and then sorts it using its sortDescriptors. A subclass could override that method to arrange the content differently.
The arranged contents can be accessed using the arrangedObjects property. This is what corresponds to rows in the table view. So, you should always use this if you're indexing by a table row. For example:
NSManagedObject *ci = [self.arrayController.arrangedObjects objectAtIndex:row];
The array controller's sortDescriptors may be set via bindings (e.g. if the table view's sortDescriptors binding is bound to the array controller). Depending on how you set up the table view bindings, this may be automatic. For NSCell-based table views, you typically bind the table columns value binding and don't bind the table views bindings. In that case, the table view automatically binds its content, selectionIndexes, and sortDescriptors bindings to the same controller as its columns. For view-based table views, you typically don't bind table columns and have to bind those table view bindings explicitly if you want them bound.
You can also set the array controller's sortDescriptors programmatically.

Answer 2

Try invoking rearrangeObjects on the NSArrayController and then doing the selection you need subsequent to that in a dispatch_async block. It's maddening, but some of the bindings are deferred to the next runloop turn, so you can't simply add an object, call rearrangeObjects, and select the new object in synchronous code. You have to use GCD to schedule things
See this question/answer for more discussion. It's is the exact same issue. Adding an object and trying to select it.

Answer 3

Enabling the Auto Rearrange Content option of the Array Controller made it for me.