Re: File's Owner

FROM : Hamish Allan
DATE : Sat May 24 14:12:51 2008

On Sat, May 24, 2008 at 1:21 AM, Johnny Lundy <<email_removed>> wrote:

> I have used it to set my class as its delegate so that I could implement the
> delegate method applicationWillTerminate:, and that was great. Easy to
> understand, it calls respondsToSelector: and then calls my delegate method.
> Cool. But as far as the "serves as a proxy for the object that owns the
> nib", why does a nib need an owner? Why do I care who the owner is? My
> NSArrayControllers can be bound to model objects without anything going
> through File's Owner.


They can indeed. You can use your nib-instantiated controller object's
awakeFromNib method to set up your model objects, and wire your main
menu's Open and Save items directly to methods in that controller. But
if you ever want to use more than one controller, you'll probably have
to start using methods like applicationDidFinishLaunching: (for
synchronisation). That code path, as well as
applicationWillTerminate:, goes through an object outside your nib
(NSApplication), even though it's subsequently calling a delegate
method inside your nib.

Incidentally, have you ever written a document-based cocoa app?

> Now if what they are trying to say is that I can bind a controller to File's
> Owner and it will "see" all the properties of all the objects in the class
> that File's Owner is set to, that would be cool.


That is exactly what they are saying.

> In that case it is just
> serving as an instance of a class and can be used to reach properties of
> objects of that class.


Well, it's serving as a *proxy* for an *existing* instance of a class.
Whereas instantiating an NSObject in the nib creates an instance and
allows you to make connections to it, you can use File's Owner to make
connections to an object that exists prior to loading of, and outside
of, the nib.

Hamish