无法启动beginBackgroundTask swift 3 [英] can't start beginBackgroundTask swift 3

问题描述

对不起，我被卡住了，但是我正在尝试启动后台任务(XCode8，迅速3)

Sorry I am stuck, but I am trying to start background task (XCode8, swift 3)

此处的示例: 在AppDelegate.swift中:

func applicationDidEnterBackground(_ application: UIApplication) {
    var bgTask: UIBackgroundTaskIdentifier = 0;
    bgTask = application.beginBackgroundTask(withName:"MyBackgroundTask", expirationHandler: {() -> Void in
        print("The task has started")
        application.endBackgroundTask(bgTask)
        bgTask = UIBackgroundTaskInvalid
    })
}

该应用程序从未显示任务已开始"消息.我在做什么错了?

The app has never shown "The task has started" message. What am I doing wrong?

推荐答案

在后台运行一段时间(通常为5分钟左右)后，将调用过期处理程序块. 如果您的后台任务要花费大量时间来完成，那么这将用于编写清理逻辑.

The expiration handler block gets called after a period of time in background (usually 5 minutes or so). This is meant to be used to write the clean up logic if in case you background task is taking a lot of time to complete.

您的代码没有错，您只需要在后台等待 即可使后台任务过期.

There is nothing wrong with your code, you just need to wait in the background for the background task to expire.

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