I am familiar with HKStatisticsCollectionQuery in HealthKit, but I am not clear how to run a query for the total number of minutes of activity in a specified time frame, rather than the total number of some QuantityType units. Is this covered somewhere in the documentation?
Perform an HKStatisticsQuery specifying the HKQuantityTypeIdentifierAppleExerciseTime quantity type to get the total number of exercise minutes for a given time period.