Re: -[NSDocument fileURL] is observable (KVO). Documented?
Re: -[NSDocument fileURL] is observable (KVO). Documented?
- Subject: Re: -[NSDocument fileURL] is observable (KVO). Documented?
- From: Mike Abdullah <email@hidden>
- Date: Tue, 1 Jun 2010 23:07:33 +0100
Precisely my point, but much better put!
In this specific case I think you should be OK since -setFileURL: is there for overriding, and AppKit bypassing it would rather miss that goal. Theoretically though, Apple could fairly happily turn off KVO-support, perhaps for performance reasons.
I'd advise subclassing to add your own notification posting code.
On 1 Jun 2010, at 22:35, Kyle Sluder wrote:
> To clarify: Mike is of course correct that any class that doesn't have
> an override of +automaticallyNotifiesObserversForKey: which returns no
> for a given key, and that always sets values of that key in a
> KVC-compliant manner, will generate KVO notifications for that key.
> And there are many Cocoa classes that have not bothered to override
> +automaticallyNotifiesObservesrForKey:. But one should *not* develop
> the expectation that most, or even a substantial portion, of Cocoa is
> KVO-compliant, because it is not.
>
> --Kyle Sluder
>
> On Tue, Jun 1, 2010 at 2:15 PM, Mike Abdullah <email@hidden> wrote:
>> By default Cocoa classes use automatic KVO. So long as Cocoa always changes the URL by calling -setFileURL: you will get proper notifications.
>>
>> On 1 Jun 2010, at 22:02, Jerry Krinock wrote:
>>
>>> There is no mention in -[NSDocument fileURL] documentation, nor in 10.5 or 10.6 release notes, that this property is observable using KVO. But when I added some code to do this, created a document, and renamed the document in Finder while the document was open, my observer logged a hit.
>>>
>>> Is there some underlying or other documentation I don't know about?
>>>
>>> Jerry Krinock
>>>
>>>
>>> - (void)observeValueForKeyPath:(NSString*)keyPath
>>> ofObject:(id)object
>>> change:(NSDictionary*)change
>>> context:(void*)context {
>>> NSLog(@"2796: keyPath %@ observed:\n%@", keyPath, change) ;
>>> }
>>>
>>> - (id)init {
>>> self = [super init] ;
>>> if (self != nil) {
>>> [self addObserver:self
>>> forKeyPath:@"fileURL"
>>> options:NSKeyValueObservingOptionNew
>>> context:NULL] ;
>>> }
>>>
>>> return self ;
>>> }
>>>
>>> - (void)dealloc {
>>> [self removeObserver:self
>>> forKeyPath:@"fileURL"] ;
>>>
>>> ...;
>>> [super dealloc];
>>> }
>>>
>>>
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