On Oct 10, 2010, at 22:31:47, Quincey Morris wrote:
> One way or another, you're going to have to come up with code to handle both
> directions of frame change: model-to-view and view-to-model. One approach is
> to use KVO observance (via [view bind:@'frame" toObject:vp
> withKeyPath:@"frame" options:0] if you really want to -- note the change of
> direction) for one direction, and have a controller object (such as a view
> controller or window controller) observe frame-change notifications from the
> view and update the model property directly.
Thanks for the attempt to explain this all to me. I wish I were smart enough to
understand it. I had assumed that -bind:... was short for "establish KVO in two
directions," but clearly that's not the case. I thought that if the two
properties were KVC/KVO-compliant, things would just work.
Since each plug-in must subclass NSViewController in order to provide a view to
display, I can provide a custom NSViewController subclass for them to use, and
put whatever code is necessary into that. But it's not clear to me exactly what
I would do, then.
The SimpleBindingsAdoption_02 sample app does this:
NSObjectController *controller = [[[NSObjectController alloc] init]
autorelease];
[controller bind:@"contentObject" toObject:self withKeyPath:@"track"
options:nil];
[textField bind:@"value" toObject:controller
withKeyPath:@"selection.volume" options:nil];
[slider bind:@"value" toObject:controller withKeyPath:@"selection.volume"
options:nil];
NSViewController has a "representedObject" property that it claims can be used
for binding, I wonder if I can point that at the plug-in instance and bind
through that property. Guess it's worth a try...
[view bind: @"frame" toObject: controller withKeyPath:
@"representedObject.frame" options: nil];
And, nope. Now the value in the model puts the view in the specified place, but
changing the view's frame does not propagate the change to the model. Does that
mean that -[NSView frame] is not KVC-compliant, or that I still need custom
code somewhere to create the binding?
--
Rick
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