Motion VS swift-collections

I think Swift Collections is adding that soon-ish, in 1.1.

Sure, those could work. But I’ve found that OrderedDictionary from the swift-collections package is really helpful in cases like this. With that, your source of truth could be OrderedDictionary. Easy constant time lookup by Section, and order is maintained.

It's a part of Swift's Collection package.

Swift Collections

I think it would be helpful if the data structure you ended up with was an OrderedDictionary, which you can use by importing the swift-collections package via spm. That way you can have an ordered reference to the month (key) and array of records for that month (value). Additionally if you need to access an specific month without knowing it’s index for some reason, it is more efficient.

In that case, use Apple's OrderedSet from swift-collections

if your ‘Dictionary’ has a lot of different keys that can vary every time, a ‘Struct’ might not be the best solution. check out ‘OrderedDictionary’ for a ‘Dictionary’ that maintains the order elements are added. https://github.com/apple/swift-collections/blob/main/Documentation/OrderedDictionary.md

You should use OrderedDictionary in swift-collections for that purpose.