如何在Azure搜索中重命名索引(How to rename index in Azure Search)

 在上面链接的iOS应用程序编程指南中，查看子标题“在后台执行有限长度任务”下的“后台执行和多任务”部分： 
 
 
 
 过渡到后台的应用程序可能需要额外的时间来完成任何重要的最后时刻任务。 要请求后台执行时间，请调用UIApplication类的beginBackgroundTaskWithExpirationHandler：方法。 如果您的应用在任务正在进行时移至背景，或者您的应用已在后台，此方法会延迟您的应用暂停。 如果您的应用正在执行一些重要任务（如将用户数据写入磁盘或从网络服务器下载重要文件），这可能很重要。 
 
 
 这给你10分钟的背景时间来做你想做的事情。 如果您注意到，Dropbox只会继续传输10分钟，然后您需要重新启动应用才能继续传输。 

In the iOS App Programming Guide, which you linked to above, look in the section "Background Execution and Multitasking" under the subheading "Executing a Finite-Length Task in the Background":
 
 
 
Apps that are transitioning to the background can request an extra amount of time to finish any important last-minute tasks. To request background execution time, call the beginBackgroundTaskWithExpirationHandler: method of the UIApplication class. If your app moves to the background while the task is in progress, or if your app was already in the background, this method delays the suspension of your app. This can be important if your app is performing some important task, such as writing user data to disk or downloading an important file from a network server.
 
 
This gives you 10 minutes of background time to do what you want. If you notice, Dropbox will only continue transferring for 10 minutes, and then you need to restart the app to get it to continue.