Let's say you have a CloudKit type called Steps, and each step record has a value and a date. If you have 500 records, is there anyway to have CloudKit pass back the sum of all the values (ex: 5,490)?
I haven't found a way besides doing a CKQueryOperation for all the steps and then manually adding them. My concern with this is that if I ended up with a lot of step records, say 5,000, that CKQueryOperation might start to limit my results.
No, this isn't possible with CloudKit. You'd have to use something that allows server functions, like Parse.
But this is a problem that is easily solved with your local device cache. If you sync your Step records with a local database (Realm, CoreData, SQLite, etc.) you can simply query all your steps in your database and add them up. This is the approach I would take.