NSDictionary, NSArray, NSSet and efficiency?

Yngvedh is correct in that an NSDictionary has O(1) lookup time (as is expected for a map structure). However, after doing some testing, you can see that NSSet also has O(1) lookup time. Here's the basic test I did to come up with that: http://pastie.org/933070.

200,000 objects sounds like you might run into memory constraints, depending on size of the objects and your target environment. One other thing you may want to consider is to convert the data into SQLite database, and then index the columns you want to do lookup on. This would provide a good compromise between efficiency and resource consumption, as you would not have to load the full set into memory.

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