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A comment from a reader of Objective-C Programming: The Big Nerd Ranch Guide came through on the forums, asking about Objective-C protocols. Specifically, why do we need them? Why do they exist?
Database-bound tests are a drag. Inconsistent tests are a pain. Database-bound, inconsistently failing tests are the worst!
The last post about isEqual: vs isEqualToString: included some timings I made to test the performance of those two calls, along with compare:. That posting mentioned going down a rabbit hole, verifying commonly held beliefs of about isEqualToString:. The other rabbit hole I went down related to the performance tuning. A couple of commenters on the post asked some good questions relating to the timings, especially about literal strings.
_TL;DR: When to use isEqual: or isEqualToString:? There’s no meaningful performance difference between the two. For convenience use isEqual:. For a modicum of type safety use isEqualToString:, but it’s not as safe as you might believe. If you have unicode strings with different normalizations, use compare:. Be careful if nils are involved.
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