Here you go:
https://mega.nz/#!kAxBQRTJ!ZqM9eHA0R-q4 ... lPRiPPXQFA
Look for the Enter key, and the Click on the save button action to see how to load a string. With the demo running type anything in the box, and enter or click save to make a few keys.
Rightclick will show you how to delete the keys, right click on the list to see how to delete the keys durring runtime.
Sorry it is not a custom example, but it should help you.
If you wanted to use my example to save a JSON look for where it says "Some random text I entered", you would put the Array json there, without any quotes.
Hope it works for you, you will see how to make a quick LSD system (Load Save Delete).
Remember also, you can make a "Save array" which you can load with other arrays, so you only have to save and load 1 string.