Re: Observer CoreData Objects changes
Re: Observer CoreData Objects changes
- Subject: Re: Observer CoreData Objects changes
- From: Ben Lachman <email@hidden>
- Date: Sun, 27 Apr 2008 00:44:53 -0400
I'm not completely clear on what you're wanting, but you might try this:
•Have your controller observe the managed object context's
NSManagedObjectContextObjectsDidChangeNotification, the userinfo of
this note contains the key NSInsertedObjectsKey and
NSDeletedObjectsKey which should let you know which objects to start/
stop observing. Make sure you read the docs about this note and when
it's sent, etc.
•In your controller call addObserver:forKeyPath:... on each of the
newly added objects that you're interested in.
In general though it is easier to bind to stuff through a pre-built
controller that is in entity mode than observe all the objects
yourself. KVO is definitely the way to go though since it gives you
change info.
HTH,
->Ben
--
Ben Lachman
Acacia Tree Software
http://acaciatreesoftware.com
email: email@hidden
twitter: @benlachman
mobile: 740.590.0009
On Apr 26, 2008, at 6:03 PM, Dex Morgan wrote:
Hello,
I need to observe from a controller class when a particular
attribute of a NSManagedObject in my persistent store is changed.
I've tried with:
- (BOOL)validateValue:(id *)value forKey:(NSString *)key error:
(NSError **)error
in my class. Unfortunatly I need to keep the old value in order to
make a comparison between it and the new value (id* value) and this
method does not allow it.
So I've tried using
- (void) addObserver:<#(NSObject *)observer#> forKeyPath:<#
(NSString *)keyPath#> options:<#(NSKeyValueObservingOptions)
options#> context:<#(void *)context#>
but the only way to keep changes of all objects is to put this
method into the init of my class (inside a subclassed method - (id)
initWithEntity:(NSEntityDescription *)entity
insertIntoManagedObjectContext:(NSManagedObjectContext *)context).
Bleah, it's not a great solution right?
Anyone can point to me to the right way?
Thanks in advanced
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