如何使用swift在应用程序中调用一次定时器？

Question

大家好我正在开发一个应用程序在我的应用程序中使用swift 2更新当前位置为每x分钟，所以我使用NSTimer能够更新位置和一切工作正常。在我的应用程序（第一视图控制器）当用户成功登录并移动到第二个视图控制器（第二视图控制器）我写了更新位置功能使用NSTimer它工作正常，但当用户移动到第三个视图控制器并返回到第二个视图控制器它再次开始更新位置，所以我无法停止定时器两次使定时器失效一次只有其他一个持续更新位置，甚至在用户注销之后。所以请有人帮我解决这个问题。

我的第二视图控制器：

class secondviewcontroller:UIViewController{ 

鉴于

做负载方法：

var appDelegate:AppDelegate = UIApplication.sharedApplication().delegate as! AppDelegate 
      appDelegate.timer = NSTimer.scheduledTimerWithTimeInterval(10.0, target: self, selector: #selector(timeToMoveOn), userInfo: nil, repeats: true) 

//i declared var timer:nstimer! in appdelegate.swift and i performed some function using nstimer 

我的第三视图控制器：

我创建了一个按钮动作为注销代码是：

var appDelegate:AppDelegate = (UIApplication.sharedApplication().delegate as? 
      AppDelegate)! 
     appDelegate.timer.invalidate() 

感谢事先

大家好感谢您的支持，我根据我的项目

Answer 1

我建议这样做：

此单包裹位置。

对不起，swift3但它有是这个样子：

class LM: NSObject, CLLocationManagerDelegate { 
    //MARK: Public Variable 

    var lat = 0.0 
    var lon = 0.0 
    var CAST = "location_cast" 
    public static let i : LM = { 
     let instance = LM() 
     return instance 
    }() 

    //MARK: Local Variable 

    fileprivate var locationManager: CLLocationManager? 

    //MARK: Init 
    public override init() { 
     super.init() 
     locationManager = CLLocationManager() 
     locationManager?.delegate = self 
    } 
    internal func start() { 
     locationManager?.startUpdatingLocation() 
    } 
    internal func stop() { 
     locationManager?.startUpdatingLocation() 
    } 
    func locationManager(_ manager: CLLocationManager, didFailWithError error: Error) { 
     //code 
     print("\(error)") 
    } 
    func locationManager(_ manager: CLLocationManager, didUpdateLocations locations: [CLLocation]) { 
     //code 
//  print("\(locations)") 
     if let loc = locations.last { 
//simple store to retrieve it later 
      lat = loc.coordinate.latitude 
      lon = loc.coordinate.longitude 


       //cast here notification 
       NotificationCenter.default.post(name: NSNotification.Name(rawValue: CAST), object: ["lat": lat, "lon": lon]) 
     } 

    } 
    func locationManager(_ manager: CLLocationManager, didChangeAuthorization status: CLAuthorizationStatus) { 
     switch status { 
     case .notDetermined: 
      manager.requestAlwaysAuthorization() 
      break 
     case .authorizedWhenInUse: 
      manager.startUpdatingLocation() 
      break 
     case .authorizedAlways: 
      manager.startUpdatingLocation() 
      break 
     case .restricted: 
      // restricted by e.g. parental controls. User can't enable Location Services 
      break 
     case .denied: 
      // user denied your app access to Location Services, but can grant access from Settings.app 
      break 
     } 
    } 
} 

启动和停止此的LocationManager使用这样的：

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

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplicationLaunchOptionsKey : Any]? = nil) -> Bool { 
// Override point for customization after application launch. 
     _ = LM.i 
     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. 

     LM.i.stop() 
    } 

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. 

     LM.i.start() 
    } 
} 

你可以在里面AppDelegate添加与铸造变量定义计时器每1秒

let CASTTOVIEWCONTROLLER = "CASTTOVIEWCONTROLLER" 
NotificationCenter.default.post(name: NSNotification.Name(rawValue: CASTTOVIEWCONTROLLER), object: ["lat": LM.i.lat, "lon": LM.i.lon]) 

或甚至简单

let CASTTOVIEWCONTROLLER_PING = "CASTTOVIEWCONTROLLER_PING" 
NotificationCenter.default.post(name: NSNotification.Name(rawValue: CASTTOVIEWCONTROLLER), object: nil) 

赶上从铸造值的新数据使用这样的：

https://stackoverflow.com/a/38615219/1979882

如果你不管理.start()如果.stop()，iOS将踢几分钟，你的背景计时器每个应用程序的将按'主页'按钮。

Answer 2

而不是从推找到了答案，我的问题

我只是不停地timer.invalidate（）两种不同的方法第三视图控制器到第二视图控制器。您可以弹出到第二个视图控制器。那么你的viewDidLoad将不会调用。

Answer 3

当我看到您的代码时，请在您的AppDelegate类中添加一个标志或Bool变量。现在，当您从第一个屏幕进入第二个屏幕时，该标志将被启用，并且当您想要导航到第三个屏幕时将false设置为标志，并且通过检查标志是否为真，您的计时器将以真实条件运行。现在，当你再次在第二屏幕从第三来临，如果计时器的情况下再然后出现PLZ参考以下链接： NSTimer Not Stopping When Invalidated

希望此举能帮助你

Answer 4

timer的目标是第二个viewController，第二个viewController拥有这个对象，AppDelegate只对这个对象引用，AppDelegate不能释放这个对象并且只有secondViewController可以。除非secondViewController是破坏

这样：

timer = NSTimer.scheduledTimerWithTimeInterval(10.0, target: self, selector: #selector(timeToMoveOn), userInfo: nil, repeats: true) 

在thirdViewController

：

let timer = (secondViewControllers object)'s timer 
timer.invalidate()