当后台服务取消挂起或重新启动时，iOS 应用程序会给出多少时间？
我有一个基于位置的 iOS 4 应用程序，它依赖于在后台监视显着的位置变化。苹果的文档指出：
在唤醒时，您的应用程序是 放入后台并给予 少量的时间来处理 位置数据。因为你的 应用程序在后台运行，它 应该做最少的工作并避免任何 任务（例如查询网络） 这可能会阻止它返回 在分配的时间到期之前。
有谁知道“一小段时间”是多长？具体来说，我想知道我是否有足够的时间在位置管理器上调用 startUpdatingLocation 以获得比初始位置事件可能提供的更准确的修复。 （我的后台位置事件几乎总是将其 horizontalAccuracy 报告为 1000m。）
如果 Apple 的“少量时间”不足以实现此目的，我是否可以调用 beginBackgroundTaskWithExpirationHandler:从后台应用程序请求更多时间？我知道这通常会给你额外的 600 秒，这已经足够了。
I have a location-based iOS 4 app that relies on significant location change monitoring while in the background. Apple's docs state:
At wake-up time, your application is
put into the background and given a
small amount of time to process the
location data. Because your
application is in the background, it
should do minimal work and avoid any
tasks (such as querying the network)
that might prevent it from returning
before the allocated time expires.
Does anyone know how long "a small amount of time is?" Specifically, I'm wondering if I have enough time to call startUpdatingLocation on a location manager in order to get a more accurate fix than what might be provided by the initial location event. (My background location events almost always report their horizontalAccuracy as 1000m.)
If Apple's "small amount of time" would be insufficient for that purpose, am I allowed to call beginBackgroundTaskWithExpirationHandler: from a backgrounded application in order to request more time? I know that usually gives you an additional 600s, which is more than adequate.
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您是否绝对需要在应用程序重新启动期间找到更准确的修复程序，或者您可以在应用程序移至前台后执行此繁重的工作，并在工作发生时显示“正在加载...”类型的屏幕吗？这将消除有关超时的任何担忧。
Do you absolutely need to find a more accurate fix during application re-launch, or can you do this heavy lifting after your app has been moved into the foreground, and show a "Loading..." type screen while the work happens? That would eliminate any concerns regarding timeouts.