Combine asynchronous return values in SwiftUI

Question

I have 2 asynchronous return values from 2 different classes, one from HealthKit, the other from MotionManager. I combine the outcome of these classes through a combinedViewModel. The code works, but I want to know if it is properly formatted and if all functions, ... are used in the right place. With other words, can I build an official app with this code or do I need to structure it differently.

MotionManager.swift

struct MotionValues {
    var rotationX: Double = 0.0
    var rotationY: Double = 0.0
    var rotationZ: Double = 0.0
    var pitch: Double = 0.0
    var roll: Double = 0.0
    var yaw: Double = 0.0
}  

class MotionManager {

    @Published var motionValues = MotionValues()

    private let manager = CMMotionManager()

    func startMotionUpdates() {
        manager.deviceMotionUpdateInterval = 1.0
        manager.startDeviceMotionUpdates(to: .main) { (data, error) in

            guard let data = data, error == nil else {
                print(error!)
                return
            }

            self.motionValues.rotationX = data.rotationRate.x
            self.motionValues.rotationY = data.rotationRate.y
            self.motionValues.rotationZ = data.rotationRate.z

            self.motionValues.pitch = data.attitude.pitch
            self.motionValues.roll = data.attitude.roll
            self.motionValues.yaw = data.attitude.yaw
        }
    }

    func stopMotionUpdates() {
        manager.stopDeviceMotionUpdates()
        resetAllMotionData()
    }

    func resetAllMotionData() {
        self.motionValues.rotationX = 0.0
        self.motionValues.rotationY = 0.0
        self.motionValues.rotationZ = 0.0
        self.motionValues.pitch = 0.0
        self.motionValues.roll = 0.0
        self.motionValues.yaw = 0.0
    }
}

HealthKitManager.swift

class HealthKitManager {

    private var healthStore = HKHealthStore()
    private var heartRateQuantity = HKUnit(from: "count/min")
    private var activeQueries = [HKQuery]()

    @Published var heartRateValue: Double  = 0.0

    func autorizeHealthKit() {

        let heartRate = HKObjectType.quantityType(forIdentifier: .heartRate)!
        let heartRateVariability = HKObjectType.quantityType(forIdentifier: .heartRateVariabilitySDNN)!

        let HKreadTypes: Set = [heartRate, heartRateVariability]

        healthStore.requestAuthorization(toShare: nil, read: HKreadTypes) { (success, error) in
            if let error = error {
                print("Error requesting health kit authorization: \(error)")
            }
        }
    }

    func fetchHeartRateData(quantityTypeIdentifier: HKQuantityTypeIdentifier ) {

        let devicePredicate = HKQuery.predicateForObjects(from: [HKDevice.local()])
        let updateHandler: (HKAnchoredObjectQuery, [HKSample]?, [HKDeletedObject]?, HKQueryAnchor?, Error?) -> Void = {
        query, samples, deletedObjects, queryAnchor, error in
            guard let samples = samples as? [HKQuantitySample] else {
                return
            }
            self.process(samples, type: quantityTypeIdentifier)
        }
        let query = HKAnchoredObjectQuery(type: HKObjectType.quantityType(forIdentifier: quantityTypeIdentifier)!, predicate: devicePredicate, anchor: nil, limit: HKObjectQueryNoLimit, resultsHandler: updateHandler)
        query.updateHandler = updateHandler
        healthStore.execute(query)
        activeQueries.append(query)
    }

    private func process(_ samples: [HKQuantitySample], type: HKQuantityTypeIdentifier) {
        for sample in samples {
            if type == .heartRate {
                DispatchQueue.main.async {
                    self.heartRateValue = sample.quantity.doubleValue(for: self.heartRateQuantity)
                }
            }
        }
    }

    func stopFetchingHeartRateData() {
        activeQueries.forEach { healthStore.stop($0) }
        activeQueries.removeAll()
        DispatchQueue.main.async {
            self.heartRateValue = 0.0
        }

    }
}

CombinedViewModel.swift

class CombinedViewModel: ObservableObject {

    @Published var motionValues: MotionValues = MotionValues()
    @Published var heartRateValue: Double = 0.0

    var motion = MotionManager()
    var health = HealthKitManager()

    var cancellables = Set<AnyCancellable>()

    init() {
        motion.$motionValues
            .combineLatest(health.$heartRateValue)
            .sink(receiveValue: { [weak self] combined  in
                self?.motionValues = combined.0
                self?.heartRateValue = combined.1
            })
            .store(in: &cancellables)
    }
}

ContentView.swift

struct ContentView: View {

    @State var isActive: Bool = false

    @ObservedObject var combined = CombinedViewModel()

    var body: some View {
        ScrollView {
            VStack(alignment: .leading) {
                Indicator(title: "X:", value: combined.motionValues.rotationX)
                Indicator(title: "Y:", value: combined.motionValues.rotationY)
                Indicator(title: "Z:", value: combined.motionValues.rotationZ)
                Divider()
                Indicator(title: "Pitch:", value: combined.motionValues.pitch)
                Indicator(title: "Roll:", value: combined.motionValues.roll)
                Indicator(title: "Yaw:", value: combined.motionValues.yaw)
                Divider()
                Indicator(title: "HR:", value: combined.heartRateValue)
            }
            .padding(.horizontal, 10)
            Button(action: {
                self.isActive.toggle()
                self.isActive ? self.start() : self.stop()
            }) {
                Text(isActive ? "Stop" : "Start")
            }
            .background(isActive ? Color.green : Color.blue)
            .cornerRadius(10)
            .padding(.horizontal, 5)
        }.onAppear {
            self.combined.health.autorizeHealthKit()
        }
    }

    private func start() {
        self.combined.motion.startMotionUpdates()
        self.combined.health.fetchHeartRateData(quantityTypeIdentifier: .heartRate)
    }

    private func stop() {
        self.combined.motion.stopMotionUpdates()
        self.combined.health.stopFetchingHeartRateData()
    }
}



struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

struct Indicator: View {

    var title: String
    var value: Double

    var body: some View {
        HStack {
            Text(title)
                .font(.footnote)
                .foregroundColor(.blue)
            Text("\(value)")
                .font(.footnote)
        }
    }
}