On Mar 1, 2010, at 08:48, Joanna Carter wrote:
> Actually, I don't really want a "dependent" property. All I want is a way to
> be able to pass a property on the main controller class to each of three
> derived array controllers, so that they can use that value to set a property
> on every new item added to the array controller.
>
> At the moment, I am manually passing the value to each of the array
> controllers in the windowControllerDidLoadNib: method of the main controller.
>
> This is fine but, since I will need to do the same thing in other scenarios,
> I wanted to create a derived array controller component that I could add to a
> NIB and setup in IB, rather than having to write the hookup code every time.
>
> - (void)windowControllerDidLoadNib:(NSWindowController *)windowController
> {
> [super windowControllerDidLoadNib:windowController];
>
> [myExtendedArrayController setExtraProperty:[self extraProperty]];
>
> ...
> }
You want to "pass a property"? What does that mean? Never mind -- it's clear
from your second paragraph that you mean "pass a value". I'm rudely pointing
this out because using precise terms precisely is important, and you've led
yourself astray multiple times in this thread by using them imprecisely.
If you don't really want a dependent property, then you certainly don't want a
binding. Bindings are a more complicated version of a dependent property.
You can achieve what you said above very simply. The cheap version goes like
this:
-- Add an IBOutlet to your NSArrayController subclass. Call it (say)
owningWindowController. Or anything you like that doesn't conflict with an
existing name.
-- When you instantiate one of these custom array controllers in IB, connect
its owningWindowController outlet to File's Owner.
-- In your custom array controller's awakeFromNib method, do the following:
myExtraProperty = [owningWindowController extraProperty];
That's it.
The classy version is only slightly more complicated:
-- Define a protocol. Call it (say) extraPropertyProviderProtocol. The protocol
contains just one thing, the "extraProperty" property definition.
-- Have your window controller formally adopt the protocol. (It already
implements it.)
-- Declare your custom array controller outlet as IBOutlet
NSObject<extraPropertyProviderProtocol>* extraPropertyProvider.
-- Connect the outlet to File's Owner, as before.
-- In your custom array controller's awakeFromNib method, do the following:
myExtraProperty = extraPropertyProvider.extraProperty;
That way, File's Owner isn't unnecessarily constrained to be a particular class
of object. It can be any object that conforms to the protocol.
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