HKWorkout objects are immutable. but iOS returns calories and other data late. how to use it?

In my healthkit based app I am thinking of using HKWorkout object.

Steps taken, energy burned and other data are late and cannot be saved at the time of creating the workout. The documentation says HKworkout objects are immutable. how do I update data that is late?

Should i wait for the relevant data and then create the object, or, is there a better way?

Thanks.
Neerav