On 24/07/2008, at 4:12 PM, Jens Alfke wrote:
On 23 Jul '08, at 9:15 PM, Steve Cronin wrote:Is this code worth it? if ([M count]>0) [M removeObject:O]; OR should I just do [M remove O];No, the first line is not worth it. You've added an extra message- send (which is _not_ cheap) to pre-check something that the NSArray (really CFArray) implementation is going to implicitly check anyway. You've also made your code harder to read, and slightly larger.
[snip]
An even better optimization, if you don't care about the order of the objects, is to use a set instead of an array. Removing an object from a large set is much, much faster than removing from a comparable array. (For NSSet it's O(1) while for NSArray it's O(n).)
I'd been wondering if there was a performance difference in general between sets and arrays - I have been building an app that uses Core Data, and ToMany relations are sets, but in some cases I have been using [xxx allObjects] (or similar, I'm not looking at the code right now).
Am I better off in general (ie, adding objects, removing objects, etc) using an NS(Mutable)Set instead of an NSArray, if I don't need sorting and duplicate items?
Matt. -- Matthew Schinckel <[EMAIL PROTECTED]> The Feynman Problem-Solving Algorithm: (1) write down the problem; (2) think very hard; (3) write down the answer.
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