ios - CloudKit count records

Question

I have a "table" that can potentially have many records, when adding a new record I need to know how many records there already are in current table as I use it in calculation of some values. The closest thing I could find is requesting all entries like this:

var query : CKQuery = CKQuery(recordType: "Stars", predicate: NSPredicate(format: "mass > 0"))
    var request : CKQueryOperation = CKQueryOperation(query: query)
    var starCount = 0

    request.queryCompletionBlock = {
        (cursor:CKQueryCursor!, error:NSError!) in
        if error {
            completionHandler(ECOResponse.error(error.description), starCount)
        } else {
            completionHandler(ECOResponse.ok(), starCount)
        }
    }

    request.recordFetchedBlock = {
        (record:CKRecord!) in
        starCount += 1
    }

I wish queryCompletionBlock gave a count or results array along with CKQueryCursor, but unfortunately it does not.

Is there any other way to calculate number of rows in the table?

Answer 1

No, it's not possible to get the total number of records that comply to your query. Also by enumerating the result the answer could be wrong. The number of records returned by CloudKit is not fixed. CloudKit has a mechanism for deciding how many records to return. It is possible to set this to a fixed number on the CKQueryOperation object. The default is:

operation.resultsLimit = CKQueryOperationMaximumResults;

The documentations for this property says:

When using that value, the server chooses a limit that aims to provide an optimal number of results that returns as many records as possible while minimizing delays in receiving those records. However, if you know that you want to process a fixed number of results, change the value of this property accordingly.

If your count is the same as this fixed number, then there are probably more records than your query returned.