How to do sparse array in Cocoa

Question

I have an undetermined size for a dataset based on unique integer keys.

I would like to use an NSMutableArray for fast lookup since all my keys are inte

Answer 1

As in Jason's answer, an NSMutableDictionary seems to be the best approach. It adds the overhead of converting the index values to and from NSNumbers, but this is a classic space/time trade off.

In my implementation I also included an NSIndexSet to make traversing the sparse array much simpler.

See https://github.com/LavaSlider/DSSparseArray