我有一个HKObserverQuery设置在后台获取步骤（enableBackgroundDelivery方法被调用在application:didFinishLaunchingWithOptions:).
这些步骤是在后台检索的，但我还想将检索到的步骤存储在 Firebase 数据库中。但这部分失败了，Firebase 中没有存储任何内容。当应用程序位于前台时，存储步骤的方法可以正常工作。任何关于如何在后台成功写入 Firebase 数据的想法将不胜感激。
class HealthKitManager {
static let shared = HealthKitManager()
private let healthStore = HKHealthStore()
private let stepsQuantityType = HKQuantityType.quantityType(forIdentifier: .stepCount)!
private init() {
}
func getTodaysStepCount(completion: @escaping (Double) -> Void) {
let now = Date()
let startOfDay = Calendar.current.startOfDay(for: now)
let predicate = HKQuery.predicateForSamples(withStart: startOfDay, end: now, options: .strictStartDate)
let query = HKStatisticsQuery(quantityType: stepsQuantityType, quantitySamplePredicate: predicate, options: .cumulativeSum) { (_, result, error) in
var resultCount = 0.0
guard let result = result else {
log.error("Failed to fetch steps = \(error?.localizedDescription ?? "N/A")")
completion(resultCount)
return
}
if let sum = result.sumQuantity() {
resultCount = sum.doubleValue(for: HKUnit.count())
}
DispatchQueue.main.async {
completion(resultCount)
}
}
healthStore.execute(query)
}
func enableBackgroundDelivery() {
let query = HKObserverQuery(sampleType: stepsQuantityType, predicate: nil) { [weak self] (query, completionHandler, error) in
if let error = error {
log.error("Observer query failed = \(error.localizedDescription)")
return
}
self?.getTodaysStepCount(completion: { steps in
// Store steps using Firebase:
StepsManager.shared.updateUserSteps(steps)
completionHandler()
})
}
healthStore.execute(query)
healthStore.enableBackgroundDelivery(for: stepsQuantityType, frequency: .hourly) { (success, error) in
log.debug("Background delivery of steps. Success = \(success)")
if let error = error {
log.error("Background delivery of steps failed = \(error.localizedDescription)")
}
}
}
}
好的，我解决了这个问题。问题是，在保存到 Firebase 实际完成之前，我正在调用completionHandler，告诉 HealthKit 我已经完成了操作。保存到 Firebase 是异步完成的。
我添加了一个完成处理程序StepsManager.shared.updateUserSteps功能：
func updateUserSteps(_ steps: Double, completion: (() -> Void)? = nil) {
let stepsReference = databaseInstance.reference(withPath: stepsPath)
stepsReference.setValue(steps) { _, _ in
completion?()
}
}
当databaseRef.setValue已完成。然后我将观察者查询更新为以下内容：
self?.getTodaysStepCount(completion: { steps in
StepsManager.shared.updateUserSteps(steps) {
completionHandler() // the HKObserverQueryCompletionHandler
}
})
Firebase 操作现已正确完成。
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