Re: Communications between multiple NIB's

FROM : Gerd Knops
DATE : Mon Mar 24 23:27:47 2008

> Is there a way to programmatically connect to a NIB file and read it's
> outlets without changing my File's Owner? I have a color well in one
> NIB (My Prefs NIB) and a window in another. I want the color well to
> change the window's background. I have an action called setColor:, but
> I cannot figure out how to access the window outlet from the NIB
> containing the window. Please help!



Given you are talking preferences, you probably do not want a direct 
connection at all but rather use the user defaults system as middle 
man, which has the additional benefit that it will save the color for 
you:

In IB select the Bindings info for your color well, and bind the value 
as follows:

Bind to: Shared Defaults
Model Key Path: myWindowBackgroundColor (or whatever)
Value Transformer: NSUnachiveFromData

Now somewhere in your application you probably want to set an initial 
default, like so:

+ (void)initialize {
   
   //
   // Register initial defaults
   //
   NSMutableDictionary *defaults=[NSMutableDictionary dictionary];
   
   [defaults setObject:[NSArchiver archivedDataWithRootObject:[NSColor 
windowBackgroundColor]] forKey:@"myWindowBackgroundColor"];
   // Set other initial defaults here
   
   [[NSUserDefaults standardUserDefaults]registerDefaults:defaults];
}


Now in your window or window controller class you want to get notified 
when that color is changed. So somewhere in -init or -awakeFromNib add 
this:

   [[NSUserDefaultsController 
sharedUserDefaultsController]addObserver:self
       forKeyPath:@"values.myWindowBackgroundColor"
       options:0
       context:nil];    

In the same class you need to implement an observer method like so:

- (void)observeValueForKeyPath:(NSString*)keyPath
                      ofObject:(id)object
                        change:(NSDictionary*)change
                        context:(void*)context
{
   if([keyPath isEqualToString:@"values.myWindowBackgroundColor"])
   {
       [self setBackgroundColorFromDefaults];
   }
}


And finally the method that sets the color:

- (void)setBackgroundColorFromDefaults {
   
   NSUserDefaults    *ud=[NSUserDefaults standardUserDefaults];
   NSColor        *bgColor=[NSUnarchiver unarchiveObjectWithData:[ud 
dataForKey:@"myWindowBackgroundColor"]];
   
   [self setColor:bgColor];
}

As last step you should probably call setBackgroundColorFromDefaults 
somewhere early in your code so that your window start out with the 
right color.

Alternatively don't set the color at all, but have the observer 
trigger a redraw, and in the drawing code read the color from the 
defaults.

Hope that helps!

Gerd