On Jul 22, 2010, at 16:37, Graham Cox wrote:
> On 23/07/2010, at 9:28 AM, Jonathon Kuo wrote:
>
>> If I use this to go backward through the array:
>>
>> for (_id in [array reverseObjectEnumerator]) {
>> }
>>
>> ...is it still considered 'fast' enumeration?
>
>
> Yes, NSEnumerator conforms to the fast enumeration protocol.
... although we don't know know (AFAIK) whether the NSEnumerator implementation
is really "fast". (It could implement the protocol, but still retrieve objects
one at a time with 'nextObject' internally. That would have similar performance
to using NSEnumerator the old way, I think.)
My guess is that the NSEnumerator class has a generic implementation that isn't
any faster, but that specific enumerators (such as NSArray, NSSet,
NSDictionary, etc) really use the underying collection's fast
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