Re: Bindings and KVO of View objects
Re: Bindings and KVO of View objects
- Subject: Re: Bindings and KVO of View objects
- From: Quincey Morris <email@hidden>
- Date: Wed, 20 May 2009 10:51:19 -0700
On May 20, 2009, at 09:24, Stuart Malin wrote:
In the specific case which I am working with, the UI element does
not correspond to a model value of the application's data. The
control is used only to change the presentation of the model data.
Hence, a change to the UI would necessitate, well, corresponding
changes to the UI. In my implementation, only the UI controller (for
this portion of the UI) is affected by the state change of the
segmented control. I guess one could make an argument for the case
that this presentation state is a model attribute of the UI.
Indeed, that situation happens, and that's not something I'd classify
as a design flaw.
On May 20, 2009, at 1:04 AM, Quincey Morris wrote:
You can bind to the selectedSegment of a segmented control, and that
will indeed produce a notification when the state of the control
changes.
It was pointed out to me what I said happens to be false.
NSSegmentedControl is not KVO-compliant for its 'selectedSegment'
property, so no notification will be produced. The spirit is willing
but the flesh is weak.
That's true of many properties of controls and other UI elements,
perhaps because it is uncommon to bind to them, as we have been
discussing. (Perhaps also, I've always speculated, because their
implementations pre-date KVO and there was no particular need to re-
implement them compliantly.)
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