Get date/time for HKQuantitySample -> heartRateSample (Watch OS2) from HealthKit

Question

I am using

-(void)updateHeartRate:(NSArray<__kindof HKSample *> *)samples

to retrieve the HearteRate from the internal watch sensor. Depending on the time the app is in background (deactivated) several heartRateSamples must be retrieved using:

if (samples.count>0) {

    for (HKQuantitySample *heartRateSample in samples) {
        dispatch_async(dispatch_get_main_queue(), ^{
            if (heartRateSample) {
            NSLog(@"HEART RATE: %@", [@([heartRateSample.quantity doubleValueForUnit:heartRateUnit]) stringValue]);
            }
        });
    }
}

but how can I retrieve the date/time when the specific sample was written to the HealthKit?

Answer 1

The quantity sample's startDate and endDate properties describe when the sample was taken:

HK_CLASS_AVAILABLE_IOS(8_0)
@interface HKSample : HKObject

@property (readonly, strong) HKSampleType *sampleType;

@property (readonly, strong) NSDate *startDate;
@property (readonly, strong) NSDate *endDate;

@end