HKAnchoredQuery update handler not working properly

Question

I wrote a code to get heart rate values from Health kit. The code is working fine but when the new heart values are updated in Health kit. I have to come to main screen and then

Answer 1

See if the following code could help you...

 HKSampleType *sampleType =
    [HKObjectType quantityTypeForIdentifier:HKQuantityTypeIdentifierHeartRate];

    HKObserverQuery *query =
    [[HKObserverQuery alloc]
     initWithSampleType:sampleType
     predicate:nil
     updateHandler:^(HKObserverQuery *query,
                     HKObserverQueryCompletionHandler completionHandler,
                     NSError *error) {

         if (error) {


             NSLog(@"error occured while setting observer. %@ ",
                   error.localizedDescription);
             abort();
         }

         // Take whatever steps are necessary to update your app's data and UI
         // This may involve executing other queries


[self executeAnchoredQuery];

         // If you have subscribed for background updates you must call the completion handler here.
         // completionHandler();

     }];

    [self.healthStore executeQuery:query];

and then the function where you write you anchoredQuery code, this may give you an idea of the code flow :

-(void)executeAnchoredQuery
{
HKSampleType *sampleType =
[HKObjectType quantityTypeForIdentifier:HKQuantityTypeIdentifierStepCount];

HKAnchoredObjectQuery *query =
[[HKAnchoredObjectQuery alloc]
 initWithType:sampleType
 predicate:nil
 anchor:self.anchor
 limit:HKObjectQueryNoLimit
 resultsHandler:^(HKAnchoredObjectQuery * _Nonnull query,
                  NSArray<__kindof HKSample *> * _Nullable sampleObjects,
                  NSArray<HKDeletedObject *> * _Nullable deletedObjects,
                  HKQueryAnchor * _Nullable newAnchor,
                  NSError * _Nullable error) {

     if (error != nil) {
         // Add proper error handling here...
         NSLog(@"*** Unable to query for step counts: %@ ***",
               error.localizedDescription);
         abort();
     }

     // Process the results...
     self.anchor = newAnchor;

     for (HKQuantitySample *sample in sampleObjects) {
         [self addStepCountSample:sample];
     }

     for (HKDeletedObject *sample in deletedObjects) {
         [self removeStepCountSample:sample];
     }

     NSLog(@"Done!");
 }];

[self.healthStore executeQuery:query];

}

Please go through apple developer docs for further details.