Re: Limited-access, KVO-compliant mutable array?
Re: Limited-access, KVO-compliant mutable array?
- Subject: Re: Limited-access, KVO-compliant mutable array?
- From: Roland King <email@hidden>
- Date: Wed, 11 Jul 2012 14:38:22 +0800
That's exactly what you do.
Declare the property as NSArray, that's what your clients see. In most cases you actually use an NSMutableArray as the backing variable so you can easily mutate it, you can either return that mutable array as the value of your property, or you can return a non-mutable copy of it. I normally return the actual array as the property is declared non-mutable so code that tries to mutate it produces lots of errors and warnings. If you're paranoid, copy it before return.
Then, in the class which owns it, either implement the KVC indexed accessor methods (like insertObject:in<Key>AtIndex:) and call those, or use [ self mutableArrayValueForKey:<Key> ] to get a mutable array which also generates the correct KVC calls. Any observer of the property will get the correct KVO calls.
On Jul 11, 2012, at 2:17 PM, Rick Mann wrote:
> I feel certain people have run into this before, but my Googling didn't turn up exactly what I was looking for.
>
> I'd like to create a "mutable read-only" array property. I want clients of the class to be able to observe changes to the *contents* of the array (that is, if an element is added or removed), in addition to changes of the entire array. But I don't want those clients to be able to add or remove anything to/from the array themselves; I only want the class on which the property is defined to be able to do that.
>
> Is this possible? My first thought is to make a read-only NSArray* property, but then it seems that addition or removal of elements to/from that property wouldn't get observed; i.e., an NSArray should never change its contents.
>
> What's the right way to do this? Thanks!
> --
> Rick
>
>
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