Question

If I use dictionaryWithObjects:forKeys:, and my array of keys happens to have duplicates, what happens? I presume the last instance of the duplicate key will be the value associated with the key; is that correct?

Answer 1

The docs say:

dictionaryWithObjects:forKeys:

…
This method steps through the objects and keys arrays, creating entries in the new dictionary as it goes.

Since a dictionary can’t have multiple entries for the same key, yes, the “steps through” strongly implies that later elements in the initializing arrays will clobber earlier ones.