Global Variables [Change Value]

So basically I have a variable that is called “Profile Picture” that is a url that is defined when the app starts.

And I want to change that variable to a new value when a person logs in.

So I want to use that variable in the img src and then when I update the variable it updates the picture

I suggest use of database (like sqlite or couch base) to store the profile picture url whenever a user does login and nullify it whenever he logs out