Version: 2019.4
public string GetInfoString ();



You will also have to implement HasPreviewGUI and OnPreviewGUI in addition to this method. The default implementation just returns an empty string, which disables the feature.

Note: Inspector previews are limited to the primary editor of persistent objects (assets). For example, GameObjectInspector, MaterialEditor, TextureInspector, and so on. This means that it is currently not possible for a component to have its own inspector preview.