I haven't used the iOS client, but on Android the most common way to sync is to use your own Git repository accessed over SSH. You could use a private GitHub repo or one on your own server.
Search for qr on the python package index using pip. There's a module that you can pipe text to and then it'll render a qr code in your terminal using Unicode glyphs. Worked well last I tried. Don't remember what the module was called but you'll be able to find it I som sure.