使用后台位置来保持NSTimer运行

Question

我试图让NSTimer在后台运行很长一段时间（多个小时）但是苹果公​​司对背景执行（10分钟）有严格的规定，但他们确实允许某些事情，如音频和在后台玩的位置。

我想知道如何使用位置管理器来保持NSTimer运行，基本上用户设置了一个“警报”。我需要它在那个时候离开，所以位置管理器保持计时器活着或类似的东西

不确定如何处理我到目前为止在我的app delegate

中有这个

@UIApplicationMain class AppDelegate：UIResponder，UIApplicationDelegate，CLLocationManagerDelegate {     var window：UIWindow？

var locationManager = CLLocationManager()
func update() {
    var backgroundMusic:AVAudioPlayer

    backgroundMusic = self.setupAudioPlayerWithFile("music", type:"mp3")
    backgroundMusic.volume = 1

    backgroundMusic.prepareToPlay()
    backgroundMusic.play()
    println("we made!")
}

func setupAudioPlayerWithFile(file:NSString, type:NSString) -> AVAudioPlayer  {
    //1
    AVAudioSession.sharedInstance().setCategory(AVAudioSessionCategoryPlayback, error: nil)
    var path = NSBundle.mainBundle().pathForResource(file as String, ofType: type as String)
    var url = NSURL.fileURLWithPath(path!)

    //2
    var error: NSError?

    //3
    var audioPlayer:AVAudioPlayer?
    audioPlayer = AVAudioPlayer(contentsOfURL: url, error: &error)

    //4
    return audioPlayer!
}

func application(application: UIApplication, didFinishLaunchingWithOptions launchOptions: [NSObject: AnyObject]?) -> Bool {
    // Override point for customization after application launch.
    if NSUserDefaults.standardUserDefaults().boolForKey(kLoadedOnceKey) == false {
        NSUserDefaults.standardUserDefaults().setBool(true, forKey: kLoadedOnceKey)
        NSUserDefaults.standardUserDefaults().setBool(false, forKey: kShouldCapitalizeTaskKey)
        NSUserDefaults.standardUserDefaults().setBool(false, forKey: kShouldCompleteNewTodoKey)
        NSUserDefaults.standardUserDefaults().synchronize()
    }

    application.registerUserNotificationSettings(UIUserNotificationSettings(forTypes: UIUserNotificationType.Sound | UIUserNotificationType.Alert |
        UIUserNotificationType.Sound, categories: nil
        ))

    return true
}

func applicationWillResignActive(application: UIApplication) {
    // Sent when the application is about to move from active to inactive state. This can occur for certain types of temporary interruptions (such as an incoming phone call or SMS message) or when the user quits the application and it begins the transition to the background state.
    // Use this method to pause ongoing tasks, disable timers, and throttle down OpenGL ES frame rates. Games should use this method to pause the game.
}

func applicationDidEnterBackground(application: UIApplication) {
    // Use this method to release shared resources, save user data, invalidate timers, and store enough application state information to restore your application to its current state in case it is terminated later.
    // If your application supports background execution, this method is called instead of applicationWillTerminate: when the user quits.
    self.locationManager.delegate = self
    self.locationManager.startUpdatingLocation()
}

func applicationWillEnterForeground(application: UIApplication) {
    // Called as part of the transition from the background to the inactive state; here you can undo many of the changes made on entering the background.
}

func applicationDidBecomeActive(application: UIApplication) {
    // Restart any tasks that were paused (or not yet started) while the application was inactive. If the application was previously in the background, optionally refresh the user interface.
}

func applicationWillTerminate(application: UIApplication) {
    // Called when the application is about to terminate. Save data if appropriate. See also applicationDidEnterBackground:.
    // Saves changes in the application's managed object context before the application terminates.
    self.saveContext()
}

// MARK: - Core Data stack

lazy var applicationDocumentsDirectory: NSURL = {
    // The directory the application uses to store the Core Data store file. This code uses a directory named "KashishGoel.Photo_Alarm" in the application's documents Application Support directory.
    let urls = NSFileManager.defaultManager().URLsForDirectory(.DocumentDirectory, inDomains: .UserDomainMask)
    return urls[urls.count-1] as! NSURL
}()

lazy var managedObjectModel: NSManagedObjectModel = {
    // The managed object model for the application. This property is not optional. It is a fatal error for the application not to be able to find and load its model.
    let modelURL = NSBundle.mainBundle().URLForResource("Photo_Alarm", withExtension: "momd")!
    return NSManagedObjectModel(contentsOfURL: modelURL)!
}()

lazy var persistentStoreCoordinator: NSPersistentStoreCoordinator? = {
    // The persistent store coordinator for the application. This implementation creates and return a coordinator, having added the store for the application to it. This property is optional since there are legitimate error conditions that could cause the creation of the store to fail.
    // Create the coordinator and store
    var coordinator: NSPersistentStoreCoordinator? = NSPersistentStoreCoordinator(managedObjectModel: self.managedObjectModel)
    let url = self.applicationDocumentsDirectory.URLByAppendingPathComponent("Photo_Alarm.sqlite")
    var error: NSError? = nil
    var failureReason = "There was an error creating or loading the application's saved data."
    if coordinator!.addPersistentStoreWithType(NSSQLiteStoreType, configuration: nil, URL: url, options: nil, error: &error) == nil {
        coordinator = nil
        // Report any error we got.
        var dict = [String: AnyObject]()
        dict[NSLocalizedDescriptionKey] = "Failed to initialize the application's saved data"
        dict[NSLocalizedFailureReasonErrorKey] = failureReason
        dict[NSUnderlyingErrorKey] = error
        error = NSError(domain: "YOUR_ERROR_DOMAIN", code: 9999, userInfo: dict)
        // Replace this with code to handle the error appropriately.
        // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
        NSLog("Unresolved error \(error), \(error!.userInfo)")
        abort()
    }

    return coordinator
}()

lazy var managedObjectContext: NSManagedObjectContext? = {
    // Returns the managed object context for the application (which is already bound to the persistent store coordinator for the application.) This property is optional since there are legitimate error conditions that could cause the creation of the context to fail.
    let coordinator = self.persistentStoreCoordinator
    if coordinator == nil {
        return nil
    }
    var managedObjectContext = NSManagedObjectContext()
    managedObjectContext.persistentStoreCoordinator = coordinator
    return managedObjectContext
}()

// MARK: - Core Data Saving support

func saveContext () {
    if let moc = self.managedObjectContext {
        var error: NSError? = nil
        if moc.hasChanges && !moc.save(&error) {
            // Replace this implementation with code to handle the error appropriately.
            // abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development.
            NSLog("Unresolved error \(error), \(error!.userInfo)")
            abort()
        }
    }
}

func locationManager(manager: CLLocationManager!, didUpdateToLocation newLocation: CLLocation!, fromLocation oldLocation: CLLocation!) {
    self.sendBackgroundLocationToServer(newLocation);
}

func sendBackgroundLocationToServer(location: CLLocation) {
    var bgTask = UIBackgroundTaskIdentifier()
    bgTask = UIApplication.sharedApplication().beginBackgroundTaskWithExpirationHandler { () -> Void in
        UIApplication.sharedApplication().endBackgroundTask(bgTask)
    }

    println(location.coordinate.latitude)

    if (bgTask != UIBackgroundTaskInvalid)
    {
        UIApplication.sharedApplication().endBackgroundTask(bgTask);
        bgTask = UIBackgroundTaskInvalid;
    }
}

}

我希望能够在NSTimer关闭时调用更新功能，有关如何设置此NSTimer的任何建议吗？

Answer 1

使用NSTimer作为警报可能不是最好的选择。正如您所知，您无法让它永远运行，更不用说用户是否终止了您的应用。此外，Apple在后台运行位置更新时对哪些应用程序获得批准非常严格。我有第一手经验。我建议你看一下使用Local Notifications来设置你的闹钟然后你就不用担心让计时器继续运行而且它会更加可靠。