Speed of NSArray#count

开发者_高级运维

If I do

[myArray count]

is it O(1) or O(n), where n is the number of elements in the array?

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The source code of Core Foundation collections (upon which Foundation collections are built) is open source. If you inspect CFArray.c, you’ll see that __CFArrayGetCount() is O(1).

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If it is not O(1) then you should find another array implementation :)