And as a side note, NSNotFound != kCFNotFound.

This has caught me out a couple of times in code that is dealing with both NS 
and CF objects.

Matt
On 18 Jan 2011, at 04:58:06, Uli Kusterer wrote:

> On 17.01.2011, at 19:50, Quincey Morris wrote:
>> In a slightly larger, conceptual sense, this means that unless you want to 
>> obsess over the specifics of *every* frameworks parameter *every* time you 
>> use one, the *practical*, everyday-use range of NSUInteger is 0 .. 
>> NSIntegerMax, not 0 .. NSUIntegerMax. In 32-bit, that's a 2 Gig item limit, 
>> not 4 Gigs.
> 
> Which is good to know if you want to use NSNotFound in your own classes, but 
> largely irrelevant if it is an index into a collection of objects, like 
> NSArray. Because in that case, just storing the pointers to these items in an 
> array (which takes 4 bytes in 32-bit, 8 in 64-bit) already restricts the 
> number of items to a value below NSIntegerMax.
> 
> After all, you'd already run out of address space around NSIntegerMax / 2 
> (NSUIntegerMax / sizeof(id), i.e. NSUIntegerMax / 4). And since you need 
> memory for system libraries, and for the NSArray and stored object(s) itself 
> (it could be an array containing the same object over and over, though), plus 
> a stack and general memory management overhead, you'll lose a few bytes more.
> 
> Considering Apple's frameworks change size with each system release, I don't 
> think there is a way to reliably calculate an upper limit. If your 
> application is likely to even vaguely get near the ballpark of NSIntegerMax / 
> 2, you should probably look into implementing a virtual memory-like mechanism 
> that swaps in/out objects from disk as needed.
> 
> -- Uli Kusterer
> Sole Janitor
> http://www.the-void-software.com
> 
> 
> 
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