当应用程序处于后台或被杀时,如何定期获取新位置

Question

当我的应用程序处于后台或被杀时,我想每1分钟获取一个新位置.这是我的代码:

定位服务:

class LocationService: NSObject, CLLocationManagerDelegate {

    static let shared = LocationService()
    var locationManager = CLLocationManager()
    var significatLocationManager = CLLocationManager()
    var currentLocation: CLLocation!
    var timer = Timer()
    var bgTask = UIBackgroundTaskInvalid

    func startUpdatingLocation() {
        locationManager.requestAlwaysAuthorization()
        locationManager.desiredAccuracy = kCLLocationAccuracyBest
        locationManager.distanceFilter = kCLDistanceFilterNone
        if #available(iOS 9.0, *) {
            locationManager.allowsBackgroundLocationUpdates = true
        }
        locationManager.delegate = self
        locationManager.startUpdatingLocation()
    }

    func stopUpdatingLocation() {
        locationManager.stopUpdatingLocation()
        timer.invalidate()
    }

    func restartUpdatingLocation() {
        locationManager.stopMonitoringSignificantLocationChanges()
        timer.invalidate()
        startUpdatingLocation()
    }

    func startMonitoringLocation() {
        locationManager.stopUpdatingLocation()
        locationManager.startMonitoringSignificantLocationChanges()
        timer.invalidate()
    }

    func changeLocationAccuracy(){
        switch locationManager.desiredAccuracy {
        case kCLLocationAccuracyBest:
            locationManager.desiredAccuracy = kCLLocationAccuracyThreeKilometers
            locationManager.distanceFilter = 99999
        case kCLLocationAccuracyThreeKilometers:
            locationManager.desiredAccuracy = kCLLocationAccuracyBest
            locationManager.distanceFilter = kCLDistanceFilterNone
        default: break
        }
    }

    func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) {
        bgTask = UIApplication.shared.beginBackgroundTask(expirationHandler: {
            UIApplication.shared.endBackgroundTask(self.bgTask)
            self.bgTask = UIBackgroundTaskInvalid
        })

        currentLocation = locations.last!

        let interval = currentLocation.timestamp.timeIntervalSinceNow
        let accuracy = self.locationManager.desiredAccuracy

        if abs(interval) < 60 && accuracy != kCLLocationAccuracyThreeKilometers {        
            timer = Timer.scheduledTimer(timeInterval: 60, target: self, selector: #selector(LocationService.changeLocationAccuracy), userInfo: nil, repeats: false)
            changeLocationAccuracy()
        }
    } 
}

应用代表:

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey: Any]?) -> Bool {
     if launchOptions?[UIApplicationLaunchOptionsKey.location] != nil {
          LocationService.shared.restartUpdatingLocation()
     }
}

func applicationDidEnterBackground(_ application: UIApplication) {
     LocationService.shared.restartUpdatingLocation()
}

func applicationWillTerminate(_ application: UIApplication) {
     LocationService.shared.startMonitoringLocation()
}

查看控制器:

override func viewDidLoad() {
    LocationService.shared.startUpdatingLocation()
}

但是我的代码无法正常工作,几分钟后,当我的应用程序处于后台时,我没有获得新的位置.当我的应用程序被暂停或杀死时也一样 那有什么解决方案吗？请注意,我使用的是Swift 3和xcode 8.1.

提前致谢

Answer 1

• 如果您startUpdatingLocation在应用程序已在后台运行时拨打电话，那么您只会收到几分钟的位置更新。

• 如果您startUpdatingLocation在应用程序位于前台时拨打电话，然后应用程序移至后台，您将继续无限期地接收位置更新。

• 如果您startMonitoringSignificantLocationChanges在前台调用并启用它，那么您可以startUpdatingLocation在后台调用并无限期地接收更新。

• 如果用户终止您的应用程序（通过在应用程序切换器中向上滑动），那么您将不再收到位置更新，直到用户重新启动您的应用程序。

由于您的代码在移动到后台时停止并启动位置监控，仅获取几分钟的位置更新。如果您在前台启动位置监控，并且当应用程序移至后台时不执行任何操作，那么您将继续接收位置更新。