How to filter NSDictionary by substring in its keys?

Question

Say I have an NSDictionary and its keys are like this:

1. @"123_000"
2. @"223_000"
3. @"123_111"
4. @"223_111"

and so on. I want to get a NSArray or NSSet of all values whose corresponding keys contain substring @"123".

Of course I can just loop over the NSDictionary, but I suspect that there must be a less code heavy approach, probably involving KVC or NSPredicate, but I'm not really good in either of them.

Answer 1

Yes, use NSPredicate.

First get allKeys from the dictionary. Then use filteredArrayUsingPredicate: to get the list of keys you want. Then use objectsForKeys:notFoundMarker: with your resulting array of keys to get the associated objects (the not found marker isn't an issue as we know all keys exist).