How do I download files to 'public' folder or the local file system

So this is a retrospective on a question I asked a few years ago. Basically, I developed a mobile app with meteor that downloaded files from a remote server and stored them on the device’s local storage system (like the app). The issue I had (mind you this is 2015) was when the app went into the background (going away to a different app), I’d go back to it and the links to the files were broken. The only way to fix it was to restart the app.

My question now is, has this issue been resolved and is there a consistent way of getting a file from a remote server and saving it on your mobile device?