On Mar 8, 2011, at 17:18, Rick Mann wrote:
> I have a UI with an editable text field and a slider. I want the two to
> represent the same model property. I only want the model updated when the
> user exits the text field or lets go of the slider (which is what it does
> now).
>
> However, I'd like it if the text field would update continuously as the
> slider is dragged.
>
> I don't think it's possible to do this with bindings, is it?
Not exactly. To get the UI behavior you want, you need to create in
intermediate property in the window controller, and bind the text field and the
slider to that.
You can make this property dependent on the model property using
'+keyPathsForValuesAffecting...'.
All that remains is to defer updating the model until the editing or sliding
operation is complete. I don't think you can do that with bindings.
Probably the simplest way to put an action on the text field and the slider.
That'll get triggered at the end of text editing, and during sliding. Something
like this (in the window controller subclass):
- (IBAction) valueChanged: (id) sender {
model.value = self.value;
}
- (IBAction) sliderValueChanged: (id) sender {
[NSObject cancelPreviousPerformRequestsWithTarget: self selector:
@selector (valueChanged:) object: nil];
[self performSelector: @selector (valueChanged:) withObject: nil
afterDelay: 0];
}
The second method (the slider's action method) is a hack to defer the action
until the user lets go of slider.
(note: code typed in Mail)
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