Apple允许后台任务运行多长时间？ [英] How long does Apple permit a background task to run?

问题描述

我必须将一组图像文件上传到数据库，因此，我偶然发现了 Apple的后台执行指南，以确保在用户暂停或终止我的应用时应用仍会上传数据。

I have to upload an array of image files to database, therefore, I stumbled upon Apple's background execution guide to make sure the app still uploads the data when user suspends or terminates my app.

但是在解释中，如果我们调用 beginBackgroundTaskWithName：expirationHandler：，则说给它一点额外的时间来完成它的工作 beginBackgroundTaskWithExpirationHandler：开始后台任务。

But in the desciption, it says giving it a little extra time to finish its work if we call beginBackgroundTaskWithName:expirationHandler: or beginBackgroundTaskWithExpirationHandler: to start a background task.

多长时间正是吗？

推荐答案

如果我错了，请纠正我，但我偶然发现了。

Correct me if I am wrong, but I have stumbled upon a perfect article from Xamarin that discusses iOS backgrounding feature.

我将简单分为两部分，ios pre 7和ios 7+：

I will simply break down to two parts, ios pre 7 and ios 7+:

答案只是 600 秒（10分钟），原因由上面的文章
提供。

The answer is simply 600 seconds (10 minutes), reason is provided by the article above.

iOS版本7 +

iOS version 7+

答案是时间系统分配给你的是机会主义。你
必须使用@Gary Riches的建议

The answer is that the time system allocates you is opportunistic. You will have to use @Gary Riches's suggestion

NSLog(@"Time Remaining: %f", [[UIApplication sharedApplication] backgroundTimeRemaining]);

查找。机会主义的原因是iOS 7+
处理后台任务的方式完全不同，当然是优化的。确切地说是
，它有间歇性的行为，因此，如果你需要
后台任务，比如下载一大堆数据，如果你使用<$，那么
会更有效c $ c> NSURLSession 而不是。

to find out. The reason for it being opportunistic is the way iOS 7+ handles background tasks is completely different, certainly optimised. To be exact, It has an intermittent behaviour, and therefore, if you need background tasks such as downloading a big chuck of data, it will be much more effective if you use NSURLSession instead.

但是，在我的特殊情况下，我上传了一个单一的对象包含一个文件准确。我不必考虑上传少量数据的 NSURLSession 。此外，它是上传任务，它可能需要花费尽可能多的时间。 ： - ）

However, in my special case, I am uploading one single object that contains one file to be exact. I do not have to consider NSURLSession for uploading a small amount of data. And besides, it's uploading task, it can take as much time as it wants. :-)

对于这些 TL; DR 访问者，上面的答案应该足够了。有关详细信息，请参阅上面的文章。

For these TL;DR visitors, the answer above should be sufficient. For more details, please refer to the article above.

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