Re: Forcing a refresh on a bound control

FROM : Scott Stevenson
DATE : Mon May 19 00:57:48 2008

On May 15, 2008, at 2:10 PM, Trent Jacobs wrote:

> What I need to do is get the NSTextView to know to reload the 
> attribute from my managed object when the checkbox changes. in other 
> words, it must know to refresh the data in Attribute X even though 
> the data in Attribute X hasn't changed.


The common solution to this is to bind the checkbox to the controller 
with a key like "shouldDisplayAsFormatted" and implement these methods 
in the controller:

   - (BOOL)shouldDisplayAsFormatted;
   - (void)setShouldDisplayAsFormatted:(BOOL)newValue;

Or even better, with Objective-C 2.0 syntax:

   @property BOOL shouldDisplayAsFormatted;

Inside the "-setShouldDisplayAsFormatted:", method, you use the input 
value to update the display of the NSTextField (which should be an 
IBOutlet).

This is not the only way to do it, but I think it's the easiest and 
cleanest way to do what you want. You probably don't want to bind the 
checkbox to the Managed Object itself because the checkbox affects a 
view on the data, not the data itself.


Hope that helps,

      - Scott