Hi there,
as a project to learn about Android programming, I made an App, that allows you to view your exposed Spark variables. This is what it may look like:
The first var is an int, but the second one is more interesting. Just write a JSONObject into your String and enjoy having more than one value in your exposed variable!
The code to construct the second var is
sprintf(tempString, "{\n\"Temp\": \"%.1f°C\",\n\"Hum\": \"%.1f%%\"\n}", t, h);
to achieve a string like
{"Temp": "19.9°C", "Hum": "47.8%"}
The third one is an Object as well, but packed with an additional JSONObject. Frankly, I was to lazy to parse anything that is more complex than a single JSONObject.
This is my very first Android App, so don’t expect it to be all perfect and beautiful. I uploaded the code to GitHub, but be prepared to cringe when you look at it 
Link to my GitHub: https://github.com/Sydenth/Spark-Variable-Reader
You’ll find the apk there as well.
I hope I’m not the only one to find this useful 
Greetings, Sydenth
PS: My App icon is an edited version of the Spark logo. I was to lazy to make something fancy and original but am not quite sure if that is legitimate.