Question

我在我的项目中实现了iBeacon识别，一切正常。当应用程序连接到具有IBeacon的BLE设备时，我将启动将数据发送到服务器的整个过程。我正在寻找一种方法来知道iOS在10秒后何时杀死应用程序以执行最后一项操作。我正在查看CLLocationManagerDelegate协议中的函数，但找不到类似于willDisconnectApplication的函数在iOS杀死我的应用程序以运行代码之前，我怎么能知道一秒钟？

Answer 1

您可以使用下面的代码段来跟踪可用的背景时间。

只需启动显示的后台任务，iOS还将为您提供额外的后台运行时间，因此您将获得180秒而不是10秒。完成此操作后，您还可以通过查看UIApplication.shared.backgroundTimeRemaining来跟踪该时间何时到期。

  private var backgroundTask: UIBackgroundTaskIdentifier = UIBackgroundTaskInvalid

  func extendBackgroundRunningTime() {
    if (self.backgroundTask != UIBackgroundTaskInvalid) {
      // if we are in here, that means the background task is already running.
      // don't restart it.
      return
    }    
    self.backgroundTask = UIApplication.shared.beginBackgroundTask(withName: "DummyTask", expirationHandler: {
      NSLog("Background running expired by iOS.  Cannot detect beacons again until a new region event")
      UIApplication.shared.endBackgroundTask(self.backgroundTask)
      self.backgroundTask = UIBackgroundTaskInvalid
    })

    if threadStarted {
      NSLog("Background task thread already started.")
    }
    else {
      threadStarted = true
      DispatchQueue.global().async {
        let startedTime = Int(Date().timeIntervalSince1970) % 10000000
        NSLog("Background task thread started")
        while (true) {
          let backgroundTimeRemaining = UIApplication.shared.backgroundTimeRemaining;
          if (backgroundTimeRemaining < 200.0) {
            if (backgroundTimeRemaining.truncatingRemainder(dividingBy: 30) < 1) {
              NSLog("Thread \(startedTime) background time remaining: \(backgroundTimeRemaining)")
            }
            else {
              NSLog("Thread \(startedTime) background time remaining: \(backgroundTimeRemaining)")
            }
          }
          Thread.sleep(forTimeInterval: 1);
        }
      }
    }
  }

Swift：iBeacon在iOS结束进程之前运行代码

1 个答案: