Hello, and thank you for your question! The "getSamples" method is not supported, but "Identify" is. "Identify" is similar to "getSamples", but not quite the same. Here's a snippet of the doc from "AGSRasterLayer":
Each raster layer supports identify on its individual cells when it is displayed in an @c AGSMapView or @c AGSSceneView.
You can use one of the "Identify" methods on the "AGSGeoView".
Let us know if you have more questions.
Mark