key-value-coding

I'm trying to work out the "correct" way to handle populating an array with key-value coding for an iPhone app. I've come up with something that works, but it's fairly hackish. Basically I'm parsing an XML document into a set of code-generated models. Let's assume the XML is of this format: <foo> <bar> <item name="baz" /> <item name="bog" /> </bar> </foo> On my generated object that represents the Bar element, I have an NSMutableArray defined for the sub-node: @interface Bar : NSObject { NSMutableArray *item; } @end So by default when I call setValue:forKey: on an instance of Bar, it ends up

I have an array of arrays that I want to use KVC on (at least I think I do -- it seems like the most straightforward way) but I can't figure out how to create keypaths for individual array indexes. My array looks like this NSArray [ NSArray[0, 1, 2, 3], NSArray[4, 5, 6, 7], NSArray[8, 9, 10, 11] ] What I want to do is get the maximum value of index 3 in the inner array. It seems like something like [outerArray valueForKey:@"@max.[3]"] would work, but I can't figure out the syntax, and my Googling has been fruitless as well. Is what I'm trying to do even possible, or should I just write a

I would like to use KVO to observe changes to the SKSpriteNode position property, but it doesn't seem to work. Is SKNode's position property observable? Nope, it is not. SK behind the scenes is a C++ engine that bypasses most of Objective-C's overhead, like for instance KVO (KVC will still work cause that's entirely on you). Unlike in UI(Kit) apps, most values of most objects change often anyway, so if you're interested in changes to a property it's faster to simply check it every frame using SKScene's update: or (better) didSimulatePhysics methods. 来源： https://stackoverflow.com/questions

I am considering using an NSMutableDictionary in place of my current NSMutableArray. This is primarily for KVC/KVO reasons. The collection will undergo heavy mutation within the inner loop of my drawing method. Can I expect to incur a significant performance hit if I go ahead with this replacement? Cheers, Doug The only way to be sure is to measure. None of us have enough knowledge about how NSMutableDictionary's and NSMutableArray's implementations work, so there's little point asking. Granted, you could probably expect some hit since the dictionary has to do additional hashing that a simple

I have a subclass of CALayer with a custom property, declared as such: @interface MyLayer : CALayer @property (nonatomic,retain) NSNumber *customValue; @end @implementation MyLayer @synthesize customValue = _customValue; @end I want to animate this property inside of an explicit CATranasction , so i set up a delegate with the actionForLayer:forKey: method implemented which returns an animation, however any changes to someMyLayerInstance.customValue inside of [CATransaction begin] ... [CATransaction end] do not result in actionForLayer:forKey getting called with a corresponding 'key' value.

In line with Apple's own recommendations, when setting KVC/KVO compliant accessors manually, one should include BOTH KVO methods willChange and didChange . This is what I have done in all my manual accessor methods. However, observeValueForKeyPath:ofObject:change:context gets called for each half of the KVC methods (will and did) with exactly the same dictionary contents. When registering an observer using the option: NSKeyValueObservingOptionPrior the observer still gets called twice - once for each half - and, again, with identically the same dictionary contents, save only the difference