Re: Weak-linking a class
Re: Weak-linking a class
- Subject: Re: Weak-linking a class
- From: Andy Lee <email@hidden>
- Date: Sun, 27 Jun 2010 09:55:16 -0400
NSClassFromString()? Or maybe some objc_xxx runtime function?
--Andy
On Jun 27, 2010, at 9:50 AM, Graham Cox wrote:
> How do I test for the existence of a Cocoa class at runtime that could be absent on an earlier system?
>
> The situation is that I want to use NSCache instead of NSMutableDictionary somewhere. The object is created as a singleton when it's first used, but I can't quite see how I should decide which class to make. I've read the weak-linking guide and it makes sense, but the example in there shows only a simple C function, not an Obj-C class.
>
> I'm setting 10.6 SDK as my base SDK, but my minimum deployment target is 10.5. Therefore NSCache will not be there on 10.5.
>
> I thought I could do e.g.:
>
> if([NSCache alloc] == nil ){ ... fall back to NSMutableDictionary ... }
>
> but on 10.6 that actually calls [NSCache alloc] which I don't want, I just want to test whether [NSCache alloc] (or any appropriate class method) actually exists or not, or more precisely, whether NSCache exists. I'm guessing it's easy and probably obvious when you know it, but I'm not seeing it.
>
> --Graham
>
>
>
>
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