Re: How to know whether property in Cocoa class is KVO-compliant?
On Jan 10, 2010, at 11:18 PM, Dave Fernandes wrote: Look for Cocoa Bindings Guide in the docs. It would be nice if it were cross-referenced in every class description. Please file a bug about that. Class methods that are KVO compatible are stated as such in the reference. They aren’t pervasive at this point, but many more became KVO compatible in Snow Leopard. I think it’s safe to expect more methods will become KVO compliant in the future. And the reference will be updated to reflect those that are. ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) 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: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
Re: How to know whether property in Cocoa class is KVO-compliant?
On Jan 10, 2010, at 19:58, Jerry Krinock wrote: After studying some about bindings during the last week, I decided that, just for fun, I would bind an NSSegmentedControl to its window controller using a binding instead of target/action. I thought that selectedSegment might be a KVO-compliant property of NSSegmentedControl because it has a -selectedSegment and -setSelectedSegment: method. So I exposed a binding named @foo in my window controller's +initialize, in -awakeFromNib I added this: [windowController bind:@foo toObject:segmentedControl withKeyPath:@selectedSegment options:0] ; Adding on to mmalc's response, to make this explicit: You *didn't* bind an NSSegmentedControl to its window controller, you actually bound a window controller['s foo binding] to [the selectedSegment property of] a NSSegmentedControl. IIRC the bindings documentation isn't clear which direction is bound to refers to and/or it gives the impression that a binding is symmetric (which it may effectively be at the level of notifications, but it isn't at the level of establishing bindings between objects). ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) 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: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
How to know whether property in Cocoa class is KVO-compliant?
After studying some about bindings during the last week, I decided that, just
for fun, I would bind an NSSegmentedControl to its window controller using a
binding instead of target/action. I thought that selectedSegment might be a
KVO-compliant property of NSSegmentedControl because it has a -selectedSegment
and -setSelectedSegment: method.
So I exposed a binding named @foo in my window controller's +initialize, in
-awakeFromNib I added this:
[windowController bind:@foo
toObject:segmentedControl
withKeyPath:@selectedSegment
options:0] ;
and finally in a windowWillClose cleanup method I added an unbind:.
The above code compiled and ran without any bitchin' from out of the console,
and at any time in the program if I send -infoForBinding:@foo to
windowController, I log the expected result:
bindingInfo = {
NSObservedKeyPath = selectedSegment;
NSObservedObject = NSSegmentedControl: 0x1b879c90;
NSOptions = {
NSMultipleValuesPlaceholder = null;
NSNoSelectionPlaceholder = null;
NSNotApplicablePlaceholder = null;
NSNullPlaceholder = null;
NSRaisesForNotApplicableKeys = 1;
NSValueTransformer = null;
NSValueTransformerName = null;
};
}
But it just didn't work. Flipping that segmented control in the user
interface never caused my window controller's -setFoo: to run.
Did I do anything wrong?
If not, I conclude that NSSegmentedControl's is not KVO-compliant for property
'selectedSegment'. That is, the class implementation probably changes the view
without invoking the setter.
I changed to target/action and it works fine.
So how does one know whether a property in Cocoa class is KVO-compliant? I
can't find an answer in the Key-Value Observing Programming Guide. I thought
maybe there's a little point system:
1. Property has a setter and getter; i.e. -bar and -setBar:. Add 2 points.
2. I remember seeing, every now and then, in newer API documentation, a
notation that this property is observeable, or something like that. Add 8
points.
3. Add 1 point for each Mac OS X dot release that the class first appeared in.
0 points for 10.0, 1 point for 10.1, etc.
4. If the class is a view layer class, subtract 2 points. Most people don't
usually bind to view classes.
5. Test it and see if it works. Add 5 points. What is the possibility that
it could stop working in a future Mac OS X release?
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Re: How to know whether property in Cocoa class is KVO-compliant?
Look for Cocoa Bindings Guide in the docs. It would be nice if it were
cross-referenced in every class description. SelectedIndex should work for a
segmented control. Haven't tried it myself though.
Cheers,
Dave
On 2010-01-10, at 10:58 PM, Jerry Krinock wrote:
After studying some about bindings during the last week, I decided that, just
for fun, I would bind an NSSegmentedControl to its window controller using a
binding instead of target/action. I thought that selectedSegment might be a
KVO-compliant property of NSSegmentedControl because it has a
-selectedSegment and -setSelectedSegment: method.
So I exposed a binding named @foo in my window controller's +initialize, in
-awakeFromNib I added this:
[windowController bind:@foo
toObject:segmentedControl
withKeyPath:@selectedSegment
options:0] ;
and finally in a windowWillClose cleanup method I added an unbind:.
The above code compiled and ran without any bitchin' from out of the console,
and at any time in the program if I send -infoForBinding:@foo to
windowController, I log the expected result:
bindingInfo = {
NSObservedKeyPath = selectedSegment;
NSObservedObject = NSSegmentedControl: 0x1b879c90;
NSOptions = {
NSMultipleValuesPlaceholder = null;
NSNoSelectionPlaceholder = null;
NSNotApplicablePlaceholder = null;
NSNullPlaceholder = null;
NSRaisesForNotApplicableKeys = 1;
NSValueTransformer = null;
NSValueTransformerName = null;
};
}
But it just didn't work. Flipping that segmented control in the user
interface never caused my window controller's -setFoo: to run.
Did I do anything wrong?
If not, I conclude that NSSegmentedControl's is not KVO-compliant for
property 'selectedSegment'. That is, the class implementation probably
changes the view without invoking the setter.
I changed to target/action and it works fine.
So how does one know whether a property in Cocoa class is KVO-compliant? I
can't find an answer in the Key-Value Observing Programming Guide. I thought
maybe there's a little point system:
1. Property has a setter and getter; i.e. -bar and -setBar:. Add 2 points.
2. I remember seeing, every now and then, in newer API documentation, a
notation that this property is observeable, or something like that. Add 8
points.
3. Add 1 point for each Mac OS X dot release that the class first appeared
in. 0 points for 10.0, 1 point for 10.1, etc.
4. If the class is a view layer class, subtract 2 points. Most people
don't usually bind to view classes.
5. Test it and see if it works. Add 5 points. What is the possibility that
it could stop working in a future Mac OS X release?
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Re: How to know whether property in Cocoa class is KVO-compliant?
On Jan 10, 2010, at 8:18 pm, Dave Fernandes wrote: Look for Cocoa Bindings Guide in the docs. It would be nice if it were cross-referenced in every class description. SelectedIndex should work for a segmented control. Haven't tried it myself though. No; the Cocoa Bindings Reference doesn't catalogue KVO compliance, it lists bindings. In general, controller objects observe model objects, and views observe controllers and models -- you typically don't bind to views. Thus you shouldn't generally expect views' properties to be observable. mmalc ___ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) 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: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com
