You should use HKStatisticsCollectionQuery:
NSCalendar *calendar = [NSCalendar currentCalendar];
NSDateComponents *interval = [[NSDateComponents alloc] init];
interval.day = 1;
NSDateComponents *anchorComponents = [calendar components:NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear
fromDate:[NSDate date]];
anchorComponents.hour = 0;
NSDate *anchorDate = [calendar dateFromComponents:anchorComponents];
HKQuantityType *quantityType = [HKObjectType quantityTypeForIdentifier:HKQuantityTypeIdentifierStepCount];
// Create the query
HKStatisticsCollectionQuery *query = [[HKStatisticsCollectionQuery alloc] initWithQuantityType:quantityType
quantitySamplePredicate:nil
options:HKStatisticsOptionCumulativeSum
anchorDate:anchorDate
intervalComponents:interval];
// Set the results handler
query.initialResultsHandler = ^(HKStatisticsCollectionQuery *query, HKStatisticsCollection *results, NSError *error) {
if (error) {
// Perform proper error handling here
NSLog(@"*** An error occurred while calculating the statistics: %@ ***",error.localizedDescription);
}
NSDate *endDate = [NSDate date];
NSDate *startDate = [calendar dateByAddingUnit:NSCalendarUnitDay
value:-7
toDate:endDate
options:0];
// Plot the daily step counts over the past 7 days
[results enumerateStatisticsFromDate:startDate
toDate:endDate
withBlock:^(HKStatistics *result, BOOL *stop) {
HKQuantity *quantity = result.sumQuantity;
if (quantity) {
NSDate *date = result.startDate;
double value = [quantity doubleValueForUnit:[HKUnit countUnit]];
NSLog(@"%@: %f", date, value);
}
}];
};
[self.healthStore executeQuery:query];