> On Sep 6, 2015, at 1:14 PM, Ken Thomases <k...@codeweavers.com> wrote:
>
> The easiest approach is to provided a class method named
> keyPathsForValuesAffecting<NameOfComputedProperty> which returns a set of key
> paths for the input properties. In Objective-C, this might look like:
>
> + (NSSet*) keyPathsForValuesAffectingMyComputedProperty
> {
> return [NSSet setWithObjects:@"inputProperty1", "otherInputProperty", nil];
> }
>
> In Swift, I expect this needs to be "dynamic", too.
Here’s the template for the keyPathsForValues… method in Swift:
private dynamic class func keyPathsForValuesAffecting<#name#>() -> Set<String> {
return [<#dependency#>]
}
Note that in Objective-C, Xcode will autocomplete this method for you, but in
Swift, it won’t. This gets fun when you realize that the above method is pretty
easy to mistype and/or misremember, so what I suggest you do is copy and paste
the code above into an Xcode code snippet, and give a keyword you can type that
will autocomplete to it (I use ‘keyPaths’, so every time I start typing
keyPaths, it’ll autocomplete to the above. It’s pretty helpful).
The “private” is so that it doesn’t show up in the public interface or
generated Obj-C headers, because it’s pretty much unnecessary clutter there.
The only code that will be calling this method is the KVC system, and it’ll be
using -respondsToSelector: rather than the public interface anyway.
Charles
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