I am making a swift iOS app that integrates with a user\'s step count as reported by the Health app. I can easily find the user\'s step count in the last hour, using this as
HKStatisticsCollectionQuery is better suited to use when you want to retrieve data over a time span. Use HKStatisticsQuery to just get the steps for a specific date.
Swift 5:
let healthStore = HKHealthStore()
func getTodaysSteps(completion: @escaping (Double) -> Void) {
    let stepsQuantityType = HKQuantityType.quantityType(forIdentifier: .stepCount)!
    let now = Date()
    let startOfDay = Calendar.current.startOfDay(for: now)
    let predicate = HKQuery.predicateForSamples(withStart: startOfDay, end: now, options: .strictStartDate)
    let query = HKStatisticsQuery(quantityType: stepsQuantityType, quantitySamplePredicate: predicate, options: .cumulativeSum) { _, result, _ in
        guard let result = result, let sum = result.sumQuantity() else {
            completion(0.0)
            return
        }
        completion(sum.doubleValue(for: HKUnit.count()))
    }
    healthStore.execute(query)
}