在CloudKit Record中添加引用

I am trying to create a record and a set of reference records in cloudkit. I first create a Category and then I add a number of locations records that reference this category. When I create the category, I use a timeStamp for the recordID and try to set that RecordID as the reference for each location record that is added. However, when I do that, I do get the category record and all of the location records created, but the reference field (named Category) is blank. This is what I am doing. What am I missing?I am trying to create a record and a set of ref