Populate Weight from HealthKit

PopulateWeight.m

HKQuantityType *weightType = [HKQuantityType quantityTypeForIdentifier:HKQuantityTypeIdentifierBodyMass];
    
// Since we are interested in retrieving the user's latest sample
// we sort the samples in descending order by end date
// and set the limit to 1
// We are not filtering the data, and so the predicate is set to nil.
NSSortDescriptor *timeSortDescriptor = [[NSSortDescriptor alloc] initWithKey:HKSampleSortIdentifierEndDate ascending:NO];

// construct the query & since we are not filtering the data the predicate is set to nil
HKSampleQuery *query = [[HKSampleQuery alloc] initWithSampleType:weightType predicate:nil limit:1 sortDescriptors:@[timeSortDescriptor] resultsHandler:^(HKSampleQuery *query, NSArray *results, NSError *error) {
    
    // if there is a data point, dispatch to the main queue
    if (results) {
        dispatch_async(dispatch_get_main_queue(), ^{
            HKQuantitySample *quantitySample = results.firstObject;
            
            // pull out the quantity from the sample
            HKQuantity *quantity = quantitySample.quantity;
            
            HKUnit *weightUnit = [HKUnit poundUnit];
            double usersWeight = [quantity doubleValueForUnit:weightUnit];
            _txtWeight.text = [NSString stringWithFormat:@"%@ lbs", [NSNumberFormatter localizedStringFromNumber:@(usersWeight) numberStyle:NSNumberFormatterNoStyle]];
        });
    }
}];

// do not forget to execute the query after its constructed
[_healthStore executeQuery:query];

Hi, I follow almost all code from you post. However, my program did not really "execute" the query. I write some NSLog (before if (results)) and debug to check and found that it never really run the code in query block.