HealthRecordPredicateQuery.swift

func getRecordUsingPredicateForAllergyType(recordReadCompletionHandler:@escaping ([HKClinicalRecord]?) -> Void) {
    
    guard let healthRecordAllergyType = HKObjectType.clinicalType(forIdentifier: .allergyRecord) else {
        fatalError("*** Unable to create the Allergy type ***")
    }
    
    let healthRecordPredicate = HKQuery.predicateForClinicalRecords(withFHIRResourceType: .allergyIntolerance)
    
    let sampleQuery = HKSampleQuery(sampleType: healthRecordAllergyType, predicate: healthRecordPredicate, limit: HKObjectQueryNoLimit, sortDescriptors: nil) { (query, samples, error) in
        guard let actualSamples = samples else {
            // Handle the error here.
            print("*** An error occurred: \(error?.localizedDescription ?? "nil") ***")
            recordReadCompletionHandler(nil)
            return
        }
        
        let healthRecordSamples = actualSamples as? [HKClinicalRecord]
        recordReadCompletionHandler(healthRecordSamples)
    }
    healthStore.execute(sampleQuery)
}