CursorAffordance.cs

using System;
using System.Collections;
using System.Collections.Generic;
using UnityEngine;

[RequireComponent(typeof(CameraRaycaster))]
public class CursorAffordance : MonoBehaviour {

    [SerializeField]
    Texture2D unknownCursor = null;

    [Serializable]
    public struct CursorLayer{
        public int Layer;
        public Texture2D Cursor;
    };

    [SerializeField]
    CursorLayer[] LayerToCursor;

    Dictionary<int, Texture2D> layerToCursor = new Dictionary<int, Texture2D>();

    private CameraRaycaster cameraRaycaster;
    
	// Use this for initialization
	void Start () {

        foreach(var i in LayerToCursor)
        {
            layerToCursor.Add(i.Layer, i.Cursor);
        }
        
        cameraRaycaster = GetComponent<CameraRaycaster>();

        cameraRaycaster.OnLayerChange += CameraRaycaster_OnLayerChange;
	}

    private void CameraRaycaster_OnLayerChange(int layer)
    {

        if(layerToCursor.ContainsKey(layer))
        {
            Cursor.SetCursor(layerToCursor[layer], Vector2.zero, CursorMode.Auto);
        } else
        {
            Cursor.SetCursor(unknownCursor, Vector2.zero, CursorMode.Auto);
        }
    }
    
    ~CursorAffordance()
    {
        cameraRaycaster.OnLayerChange -= CameraRaycaster_OnLayerChange;
    }

}

CursorAffordanceEditor.cs

using UnityEditor;
using UnityEngine;

// TODO consider changing to a property drawer
[CustomEditor(typeof(CursorAffordance))]
public class CursorAffordanceEditor : Editor
{
    bool isLayerPrioritiesUnfolded = true; // store the UI state

    public override void OnInspectorGUI()
    {
        serializedObject.Update(); // Serialize CursorAffordance instance

        isLayerPrioritiesUnfolded = EditorGUILayout.Foldout(isLayerPrioritiesUnfolded, "Layer Cursors");
        if (isLayerPrioritiesUnfolded)
        {
            EditorGUI.indentLevel++;
            {
                BindArraySize();
                BindArrayElements();
            }
            EditorGUI.indentLevel--;
        }

        serializedObject.ApplyModifiedProperties(); // De-serialize back to cameraRaycaster (and create undo point)
    }

    void BindArraySize()
    {
        int currentArraySize = serializedObject.FindProperty("LayerToCursor.Array.size").intValue;
        int requiredArraySize = EditorGUILayout.IntField("Size", currentArraySize);
        if (requiredArraySize != currentArraySize)
        {
            serializedObject.FindProperty("LayerToCursor.Array.size").intValue = requiredArraySize;
        }
    }

    void BindArrayElements()
    {
        int currentArraySize = serializedObject.FindProperty("LayerToCursor.Array.size").intValue;
        for (int i = 0; i < currentArraySize; i++)
        {
            var prop = serializedObject.FindProperty(string.Format("LayerToCursor.Array.data[{0}].Layer", i));
            prop.intValue = EditorGUILayout.LayerField(string.Format("Layer {0}:", i), prop.intValue);

            var texprop = serializedObject.FindProperty(string.Format("LayerToCursor.Array.data[{0}].Cursor", i));
            
            texprop.objectReferenceValue = EditorGUILayout.ObjectField(string.Format("Cursor {0}:", i), texprop.objectReferenceValue, typeof(Texture2D), true);
        }
    }
}