• Open Menu Close Menu
  • Apple
  • Shopping Bag
  • Apple
  • Mac
  • iPad
  • iPhone
  • Watch
  • TV
  • Music
  • Support
  • Search apple.com
  • Shopping Bag

Lists

Open Menu Close Menu
  • Terms and Conditions
  • Lists hosted on this site
  • Email the Postmaster
  • Tips for posting to public mailing lists
KVO: I get called on change, but then can't get the object
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

KVO: I get called on change, but then can't get the object


  • Subject: KVO: I get called on change, but then can't get the object
  • From: Rick Mann <email@hidden>
  • Date: Sat, 31 May 2008 00:21:09 -0700

I registered to observe changes in the "number" column of my tree controller:

	[mItemsController addObserver: self
		forKeyPath: @"selection.number"
		options: (NSKeyValueObservingOptionNew)
		context: NULL];

My -observe: action gets called, but this line

NSLog(@"Value changed %@: %@ (%@)", inKeyPath, inChange, [inObject selection]);


dumps this to the console:

Value changed selection.number: {
    kind = 1;
    new = <null>;
} (<_NSControllerObjectProxy: 0x177cb0>)

Note that "new" is null. I would expect it to be the value of the number.

Furthermore, this line:

	NSLog(@"selection: %@", [inObject valueForKey: @"selection"]);

dumps:

	selection: <_NSControllerObjectProxy: 0x177cb0>

But if I change it to @"selection.number", it throws the exception:

"[<NSTreeController 0x1722e0> valueForUndefinedKey:]: this class is not key value coding-compliant for the key selection.number."



From reading the docs:

"NSObjectController and its subclasses implement the selection method. This method returns a proxy object that represents the receiver’s current selection. The proxy is fully key-value-coding compliant.
When you request a key’s value from the selection proxy it returns the value, or a selection marker. Placeholder markers provide additional information about the selection. There are three placeholder markers defined in the NSPlaceholders informal protocol:"


It seems that I should be able to get the number from the selection, but instead I get the exception:

"[<NSTreeController 0x170c60> valueForUndefinedKey:]: this class is not key value coding-compliant for the key selection.number."



I feel like I should be able to get the number. Elsewhere I read that I would get an array of numbers. What am I doing wrong?



TIA,




-- Rick

_______________________________________________

Cocoa-dev mailing list (email@hidden)

Please do not post admin requests or moderator comments to the list.
Contact the moderators at cocoa-dev-admins(at)lists.apple.com

Help/Unsubscribe/Update your Subscription:
This email sent to email@hidden


  • Follow-Ups:
    • Re: KVO: I get called on change, but then can't get the object
      • From: Scott Anguish <email@hidden>
    • Re: KVO: I get called on change, but then can't get the object
      • From: j o a r <email@hidden>
  • Prev by Date: Re: super respondsToSelector
  • Next by Date: Re: super respondsToSelector
  • Previous by thread: Re: How can i get current system time?
  • Next by thread: Re: KVO: I get called on change, but then can't get the object
  • Index(es):
    • Date
    • Thread