3分钟后继续后台任务

Question

I tried the answer of this question

How can a connection started with NSURLConnection while in the foreground be continued in the background?

And works like a charm! but only for 3 minutes in background, then iOS sends the app to sleep, Im trying to upload n videos and 3 minutes is not enought to send all data, I also readed that I can change my NSURLConnection to NSURLSession but I have no idea how to start that or how much time it takes.

Is there a way to keep background task alive after 3 minutes and until upload ends?

Answer 1

Is there a way to keep background task alive after 3 minutes and until upload ends?

No, there isn't. On-going background execution is limited to very narrow purposes (eg playing music, VOIP apps, navigation apps, etc.). All of this is outlined in the Background Execution section of the App Programming Guide for iOS.

I also [read] that I can change my NSURLConnection to NSURLSession but I have no idea how to start that or how much time it takes.

Yes, this is correct. If you want network request to continue for more than a few minutes after the app enters background, you should use NSURLSession with a background NSURLSessionConfiguration . See Downloading Content in the Background in the App Programming Guide for iOS for more information. See WWDC 2013 What's New in Foundation Networking for introduction to NSURLSession , including a demonstration on how to do background session.

I'd suggest you tackle this in two steps: First, convert to NSURLSession , and second, enable background NSURLSession operation. I think you'll find this first step is pretty easy. All of the concepts are very familiar. The only trick is that NSURLSession has two types of interfaces, delegate-protocol pattern and completion handlers. If you plan on using this for background operation later, you'll want to stick with the delegate-protocol pattern because the simpler completion handler pattern is not compatible with background sessions. And you'll want to use the upload task method that uploads from a file (don't use the stream-based rendition).

This second step, enabling background operation, isn't hard, but it can be tricky, though, simply because it involves a few new little details that we haven't had to worry about in the past (eg the app delegate code to capture (and later call) the completion handler for background sessions). Also, when you start debugging background session code, it can be disorienting to have requests initiated by one debugging session to show up in the next debugging session (hey, they're background sessions that are supposed to keep running when your app is terminated, after all). It's not a problem, but can be a bit disorienting.