Re: NSObjectController HELP
Re: NSObjectController HELP
- Subject: Re: NSObjectController HELP
- From: mmalcolm crawford <email@hidden>
- Date: Sun, 6 Jun 2004 00:52:46 -0700
On Jun 6, 2004, at 12:15 AM, Vince Ackerman wrote:
The docs for the controller objects reference changing the instance
variables without accessor methods....
Where?
I think it might be reasonable to suggest that it be made explicit
somewhere that you must use accessor methods, however:
"The main requirement to make use of KVO is that your model objects be
KVO-compliant. In most cases this actually requires no effortthe
runtime system adds support automatically. By default, all invocations
of KVC methods result in observer notifications. You can also implement
manual supportsee Key-Value Observing for more details."
<
http://developer.apple.com/documentation/Cocoa/Conceptual/
CocoaBindings/Concepts/HowDoBindingsWork.html>
I thought that was the whole point? What is it that the controller is
doing then...? I was under
the impression that the NSObjectController was responsible through KVO
to update the bound object.
No, as the above document makes clear, the bound object observes the
controller and updates itself accordingly (see "Responding to
Changes").
It observers the instance variable and updates the bound object as the
variable changed. If I have to write special accessor methods then I
might as well go back and put my glue code using IBOutlet's and
notifications back in my project...... Not much of a labor saving
device if that's the case.
There's a significant difference between writing accessor methods that
you should really be writing anyway and writing the glue code...
Are you saying my floats and Booleans have to be NSNumber objects and
use those set/get methods?
No, as the documentation on KVC/KVO makes clear, you can use scalar
values. KVC/KVO will automatically convert scalars to appropriate
objects.
<
http://developer.apple.com/documentation/Cocoa/Conceptual/
KeyValueCoding/Concepts/DataTypes.html>
So far I haven't been able to get it to update the NSString obj
either.......
I suspect that's a different problem. What are the circumstances?
mmalc
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