How to use NSURLSession to download and save a file

I'm creating an app that needs to download and save a large file (over 600MB). For android I'll be using WebClient.DownloadFileAsync, but I have read that it is recomended to use NSURLSession for iOS. I do want the file to continue downloading in the background if possible, but it isn't required. I also need to be able to read the download progress of the file. Does anyone know how to do this in unity? Thanks.

 

I use webclient.downloadfileasync on ios and have no issues... when you say 'in the background' do you mean, when the app is swapped to the background to run a different app? reason to ask is that webclient will run on a different thread without a problem and has progress capability.

 

Thanks. Running while the application is paused is mainly important for GearVR since it pauses if you take the headset off. On iOS it doesn't really need to be able to do that. Though might be nice if it could download while the application is in the background and the user is in another app. It's not necessary. I'll use WebClient for now.

 

Just a word of advice from my experience, make sure to put in something to cancel webclient downloads (or something similar) incase the user decides to suspend your app. I haven't checked to see if the background thread used by webclient gets suspended or not, but I had a case where a user did so for some other apps and the unity app got killed.. corrupting the download.

Code (CSharp):

1.        
2.  
3. //ONAPPPAUSED
4.        //where client is the instance of webclient used to begin fileasyncdownload
5.         void OnApplicationPause(bool pauseStatus)
6.         {
7.             if (pauseStatus)
8.             {
9.                 client.CancelAsync();
10.             }
11.         }
12.  
13.  

 

I also want to include a cancel download button for the user if they want to stop it. I'm guessing I would call client.cancelAsync(); for that too. Will doing that remove the partially downloaded file or do I need to delete the file after canceling? I'm currently downloading to the PersistantDataPath.
Thanks.

 

Also what is the (bool pauseStatus) for? Is that different than just using:

Code (CSharp):

1. void OnApplicationPause(){
2. client.CancelAsync();
3. }