Testing API data

[Benji]

1. Is there a way to test API outputs in my project if it’s not used in the UI.
   For example in my Project I receive a color from an API but the color is just a value in the backend.
2. After checking for API data, can I compare it by writing it in a table (API testing data vs. preset API data) then reading that table to see if it matches and return to testing script for a pass/fail status?
3. Will any of the languages Appium supports be able to do this?
4. Can this be performed on both iOS and Android?

[VikramVI]

API testing is best done with rest-assured.

[Benji]

Do you have any recommendations on how to access a variable from the app code? Just viewing it that way I can test against it.