Cocoa - Notification on NSUserDefaults value change?

Let's say I have a key @"MyPreference", with a corresponding value stored through NSUserDefaults.

Is there a way to be notified when the value is modified?

Or could it be done through bindings? (But this case, instead of binding the value to a UI element, I wish my object to be notified of the change, so that I can perform other tasks.)

I am aware that NSUserDefaultsDidChangeNotification can be observed, but this appears to be a all-or-nothing approach, and there does not appear to be a mechanism there to get at the specific key-value-pair that was modified. (Feel free to correct.)

Spent all day looking for the answer, only to find it 10 minutes after asking the question...

Came across a solution through Key-Value-Observing:

[[NSUserDefaultsController sharedUserDefaultsController] addObserver:self
    forKeyPath:@"values.MyPreference"
    options:NSKeyValueObservingOptionNew
    context:NULL];

Or, more simply (per comment below):

[[NSUserDefaults standardUserDefaults] addObserver:self
                                        forKeyPath:@"MyPreference"
                                           options:NSKeyValueObservingOptionNew
                                           context:NULL];

Swift:

override func viewDidLoad() {
  super.viewDidLoad()
  NSUserDefaults.standardUserDefaults().addObserver(self, forKeyPath: "THE KEY", options: NSKeyValueObservingOptions.New, context: nil)
}

override func observeValueForKeyPath(keyPath: String, ofObject object: AnyObject, change: [NSObject : AnyObject], context: UnsafeMutablePointer<Void>) {
  // your logic
}

deinit {
  NSUserDefaults.standardUserDefaults().removeObserver(self, forKeyPath: "THE KEY")
}

And Apple employee advised to use NSUserDefaultsDidChangeNotification notification over here: https://devforums.apple.com/message/237718#237718

I agree with @DenNukem. I was using the NSKeyValueObservingOptionNew. But this function started giving me the BAD_ACCESS Code=1 error wherever I used the NSUserDefault in order to save other objects. In case you are using Key-Value Observer (KVC), just be aware of the Zombie issue on NSUserDefaults.

Here is the link to the solution: https://stackoverflow.com/questions/5714161/nsuserdefaults-and-kvo-issues