Saving and loading user data in a deployed shiny app

I am trying to write a shiny app and let the user save and later reload their inputs. I have it working running the app from RStudio using the shinyFiles package. However when I deploy it to I can only save and load to the app's own file space, which is shared by all users. I would prefer to save and load to a user's own computer/file system. How do I do this? Thanks.

Ok, this is actually quite easy with downloadButton and fileInput, although fileInput isn't as flexible as I'd like. I'd prefer just to have a button.