On Oct 26, 2008, at 3:21 PM, Nathan Kinsinger wrote:
On Oct 26, 2008, at 2:05 PM, john fogg wrote:
Hi again!
Thank you everybody for your answers.
On Sun, Oct 26, 2008 at 7:45 PM, Andy Lee <[EMAIL PROTECTED]> wrote:
I don't know Actionscript but it looks like it has a global
dictionary of
objects that you can reference by name. There is nothing like
"_root" in
Objective-C.
I see, this is where I was wrong. Yes Actionscript has this global
dictionary. If you know the name of an object and its place in the
hierarchy you can access it.
In my game I think of having a sort of "controller object" that
controls the whole state of the game. So I'd like to access it from
almost every other object further down the hierarchy. How would you
do
this?
Is there a way to create the controller object and store its
reference
in a global variable? Or is there another common way to do this that
I'm not thinking of?
Sorry for asking such dumb questions but I'm still new to this.
Thanks again in advance!
(not a dumb question)
You want to use the singelton pattern, see:
http://developer.apple.com/documentation/Cocoa/Conceptual/CocoaFundamentals/CocoaObjects/chapter_3_section_10.html
Well, you don't necessarily need a singleton object or the global
variable that you (John) are considering.
You should familiarize yourself with the Model-View-Controller (MVC)
design pattern that's fundamental to Cocoa. A button would usually
only talk directly to its controller. The controller is then
responsible for knowing what other object(s) within its sphere of
control needs to be messaged. If you feel that some other object
outside of the immediate controller's sphere needs to be messaged,
then you should forward the message up to a higher-level controller
which controls the wider sphere.
Each controller should be connected to the objects which it controls.
This is often done by connecting up outlets in nibs. Even when
dealing with a view hierarchy, it's more common for the controller to
have an outlet to a control deep in the hierarchy than it is for it to
navigate the hierarchy starting from the top.
An important note: the names you give to objects in a nib are only
cosmetic and are only meaningful when editing the nib. You can't
access those objects by name in your code.
Typically, you'll have an application controller object. It will be
an instance of a custom subclass of NSObject. Often it will be the
application delegate, too.
This application controller will be the central organizer of your
application. It will typically have references to your other
application objects -- model objects, documents and/or document
controllers, windows and/or window controllers, etc. If it doesn't
have a direct reference to one of these, it probably has an indirect
reference. That is, it has a reference to an object which has a
reference to the desired thing.
Also, each of those objects usually has a path back to the application
controller. If the application controller is the application
delegate, then that's easy: [NSApp delegate] gets you the reference to
the object.
Window controllers often act as the "File's Owner" for nibs which
contain a window. You hook up outlets from the window controller to
the window being controlled and, if desired, to specific views/
controls within the window.
Using some combination of the above patterns, you will usually find
that's its straightforward to get a reference to the object you need.
Does that help?
Cheers,
Ken
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