multiple thread in assembly language

Question

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
    //***********************************************************************************************************
    // requesting access and autherzation and availability
    let healthStore = HKHealthStore()
    if HKHealthStore.isHealthDataAvailable() {
        calciumTracker.setProgress(0.1, animated: true)
        let ShareTypes : Set = [HKSampleType.quantityTypeForIdentifier(HKQuantityTypeIdentifierStepCount)!]
        let ReadTypes : Set = [HKCharacteristicType.characteristicTypeForIdentifier(HKCharacteristicTypeIdentifierBiologicalSex)!]
        healthStore.requestAuthorizationToShareTypes(ShareTypes, readTypes: ReadTypes , completion:{
            (success,error) in
            if !success {
                if let x = error {
                    print(x.description)
                }

            }
        })
    }
    else {
        print("Health data are not available on this device")
    }
    //***********************************************************************************************************
    let endDate = NSDate()
    let startDate = NSDate()
    var v : HKQuantitySample?
    let stepsCount:HKQuantityType = HKQuantityType.quantityTypeForIdentifier(HKQuantityTypeIdentifierStepCount)!
    let predicate:NSPredicate = HKQuery.predicateForSamplesWithStartDate(startDate, endDate: endDate, options: .None)
    let limit = 1
    let query = HKSampleQuery(sampleType: stepsCount, predicate: predicate, limit: limit, sortDescriptors: nil, resultsHandler: {
        (query, results, error) in
            if results == nil {
                print(error)
            }
            v = results!.first as! HKQuantitySample?
        })
    healthStore.executeQuery(query)
    let l = Float(v!.quantity.doubleValueForUnit(HKUnit(fromString: "count")))
    stepsTracker.setProgress(l/300, animated: true)
}

when i run the app it get stuck on the launch screen and Xcode tell me there is threads an list them i do not understand any of them because i think they are in assembly language

You need to read up on how asynchronous methods work in iOS. You should put code that relies on the completion of any asynchronous methods inside the completion handlers. — dan, Aug 07 '15 at 18:45

score 0 · Answer 1 · answered Aug 07 '15 at 19:42

The crash is caused by unwrapping value from nil object. The app tries to access HKQuantitySample even if it's nil, it crashes in this line:

let l = Float(v!.quantity.doubleValueForUnit(HKUnit(fromString: "count")))

You should re-organize the logic and execute the second half of the codes in the callback of the requestAuthorizationToShareTypes function.

For example:

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.
    //***********************************************************************************************************
    // requesting access and autherzation and availability
    let healthStore = HKHealthStore()
    if HKHealthStore.isHealthDataAvailable() {
        calciumTracker.setProgress(0.1, animated: true)
        let ShareTypes : Set = [HKSampleType.quantityTypeForIdentifier(HKQuantityTypeIdentifierStepCount)!]
        let ReadTypes : Set = [HKCharacteristicType.characteristicTypeForIdentifier(HKCharacteristicTypeIdentifierBiologicalSex)!]

        healthStore.requestAuthorizationToShareTypes(ShareTypes, readTypes: ReadTypes , completion:{
            (success,error) in
            if !success {
                if let x = error {
                    print(x.description)
                }
            } else {
                //***********************************************************************************************************
                let endDate = NSDate()
                let startDate = NSDate()
                var v : HKQuantitySample?
                let stepsCount:HKQuantityType = HKQuantityType.quantityTypeForIdentifier(HKQuantityTypeIdentifierStepCount)!
                let predicate:NSPredicate = HKQuery.predicateForSamplesWithStartDate(startDate, endDate: endDate, options: .None)
                let limit = 1
                let query = HKSampleQuery(sampleType: stepsCount, predicate: predicate, limit: limit, sortDescriptors: nil, resultsHandler: {
                    (query, results, error) in
                    if results == nil {
                        print(error)
                    }
                    v = results!.first as! HKQuantitySample?
                })
                healthStore.executeQuery(query)
                let l = Float(v!.quantity.doubleValueForUnit(HKUnit(fromString: "count")))
                self.stepsTracker.setProgress(l/300, animated: true)
            }
        })
    }
    else {
        print("Health data are not available on this device")
    }
}

Ideally, before you request the authorization, you should check the authorization status first, i.e, call authorizationStatusForType().

multiple thread in assembly language

1 Answers1