Testing NativeScript app with Appium
Part-1 : Views are created using xml which must have attributes like text,name,css
etc. These are accessible using methods like By.name,By.cssSelector
etc. depending on the attributes provided during development.
Part-2 : I believe since Appium was built on selenium initially and supports majority of its functionality. You can go ahead and try something similar to this and you can provide action to your suite accessing the objects as in Part-1. To run the tests created would require similar efforts to run your main test script.
Look this closed issue at github: https://github.com/NativeScript/NativeScript/issues/553
You don't have access to internals of your app :( (when you use appium for tests, but why you don't take a look in KIF, you access elements by using accessibility label or accessibility identifier, it's more simple. Hope helps :)