Am 01.02.2010 um 16:35 schrieb Charles Jenkins:
> On 2010-02-01 03:26, Roland King wrote:
>>
>> By the way, CALayer is a KVC compliant class so you can in fact just store a
>> reference to an arbitrary object in it with
>>
>> [ layer setValue:value forKey:@"KeyForObjectAssociatedWithLayer" ];
>
> Roland, I'm a noob and I'm not sure I've got a good handle on KVC yet... This
> statement really looks interesting to me, because it seems to suggest that
> with a KVC-compliant class, you can make arbitrary linkages by just making up
> keys.
This is a wrong assumption.
Most classes are KVC compliant but you can not invent keys. You just use
existing keys - properties and methods.
> (I checked the documentation, and haven't found any property named
> objectAssociatedWithLayer, so I'm assuming that you were able to create this
> key name yourself and name it whatever you liked.) Is this true or have I
> totally misunderstood you?
Read "Core Animation Extensions To Key-Value Coding" to get some enlightenment
;)
"Both CALayer and CAAnimation are key-value coding compliant container classes,
allowing you to set values for arbitrary keys. That is, while the key “foo” is
not a declared property of the CALayer class, however you can still set a value
for the key “foo” as follows:"
The important thing is, that they are container classes. Like NSDictionary.
This is not true for all classes.
atze
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