Clear View Data When Tab is Changed SwiftUI - swift

Question

I am showing daily step information in one of the tabs. Unfortunately, when I select the steps tab again it adds one more of the same data below the previous one.
I have tried to solve it via toggle a boolean. But it did not help either.
import SwiftUI
import HealthKit
struct StepView: View {
private var healthStore: HealthStore?
#State private var presentClipboardView = true
#State private var steps: [Step] = [Step]()
init() {
healthStore = HealthStore()
}
private func updateUIFromStatistics(_ statisticsCollection: HKStatisticsCollection) {
let now = Date()
let startOfDay = Calendar.current.startOfDay(for: now)
statisticsCollection.enumerateStatistics(from: startOfDay, to: now) { (statistics, stop) in
let count = statistics.sumQuantity()?.doubleValue(for: .count())
let step = Step(count: Int(count ?? 0), date: statistics.startDate, wc: Double(count ?? 0 / 1000 ))
steps.append(step)
}
}
var body: some View {
VStack {
ForEach(steps, id: \.id) { step in
VStack {
HStack{
Text("WC")
Text("\(step.wc)")
}
HStack {
Text("\(step.count)")
Text("Total Steps")
}
Text(step.date, style: .date)
.opacity(0.5)
Spacer()
}
}
.navigationBarBackButtonHidden(true)
}
.onAppear() {
if let healthStore = healthStore {
healthStore.requestAuthorization { (success) in
if success {
healthStore.calculateSteps { (statisticsCollection) in
if let statisticsCollection = statisticsCollection {
updateUIFromStatistics(statisticsCollection)
}
}
}
}
}
}
.onDisappear() {
self.presentClipboardView.toggle()
}
}
}
Step Model
struct Step: Identifiable {
let id = UUID()
let count: Int?
let date: Date
let wc: Double
}
HealthStore file
class HealthStore {
var healthStore: HKHealthStore?
var query: HKStatisticsCollectionQuery?
init() {
if HKHealthStore.isHealthDataAvailable() {
healthStore = HKHealthStore()
}
}
func calculateSteps(completion: #escaping (HKStatisticsCollection?) -> Void ) {
let stepType = HKQuantityType.quantityType(forIdentifier: HKQuantityTypeIdentifier.stepCount)!
let now = Date()
let startOfDay = Calendar.current.startOfDay(for: now)
let daily = DateComponents(day:1)
let predicate = HKQuery.predicateForSamples(withStart: startOfDay, end: Date(), options: .strictStartDate)
query = HKStatisticsCollectionQuery(quantityType: stepType, quantitySamplePredicate: predicate, options: .cumulativeSum, anchorDate: startOfDay, intervalComponents: daily)
query!.initialResultsHandler = { query, statisticCollection, error in
completion(statisticCollection)
}
if let healthStore = healthStore, let query = self.query {
healthStore.execute(query)
}
}
func requestAuthorization(completion: #escaping (Bool) -> Void) {
let stepType = HKQuantityType.quantityType(forIdentifier: HKQuantityTypeIdentifier.stepCount)!
guard let healthStore = self.healthStore else { return completion (false) }
healthStore.requestAuthorization(toShare: [], read: [stepType]) { (success, error) in
completion(success)
}
}
}
Those are all related files according to my problem.
Thanks in advance.

Answer 1

The steps is annotated with #State which means it will be persisted even when the view is redrawn.
And you never reset it. You only append new steps. Try clearing steps in updateUIFromStatistics:
private func updateUIFromStatistics(_ statisticsCollection: HKStatisticsCollection) {
steps = [] // remove previous values
let now = Date()
let startOfDay = Calendar.current.startOfDay(for: now)
statisticsCollection.enumerateStatistics(from: startOfDay, to: now) { (statistics, stop) in
let count = statistics.sumQuantity()?.doubleValue(for: .count())
let step = Step(count: Int(count ?? 0), date: statistics.startDate, wc: Double(count ?? 0 / 1000 ))
steps.append(step)
}
}