Dictionary in inspector

You could just do a hack, like you do for anything serious in unity.

expose a normal array.

 [Serializable]
 public struct NamedImage {
     public string name;
     public Texture2D image;
 }

 public NamedImage[] pictures;

then at the Start() or Awake(), or whenever your mind is flipped for it. put the array manually in a Hash or Dictionary or whatever. It looks alright in the inspector.

If it looks like a Hashtable, walks like a Hashtable, acts like a Hashtable, guess what, its a Hashtable.

Use ISerializationCallbackReceiver to let Unity serialize the keys and values of your dictionary. From there, you can access both lists and create your custom editor.

It's a PITA but you'd have to do the rendering yourself. Also note that Unity will not serialize/save/load dictionary for you. For this reason, a lot of people store things in Lists and then build a Dictionary at Start to make lookups faster.

I was just facing this problem. I tried some custom serialization, to find that it gives me trouble when switching to the HTML5 platform. I am not really savvy on serialization and its shenanigans, so I needed to implement a different solution.

In the end, my solution is a variation on the hack @Helical described:

1. Using platform-dependent compilation, I declare a serialized key-value struct for the dictionary I want to fill, and an array of this struct. This struct, array, and the function to use them, will only exist for the editor.
   
   

2. Create a scriptable object to contain the dictionary. This object I will be using in the game.
   
   

3. Run an editor function that stores the data from the array into the dictionary in the scriptableObject. Since it is an asset, you will need to use the AssetDatabase class to 1) set it dirty before modifying it; 2) save the AssetDatabase, 3) reload the assetDatabase.
   
   The result is a visible list of items available in the editor, a plain old dictionary that will leave no extra trash and require no extra processing in the application, and an editor function that saves the first into the second.
   
   

Of couse, as some have mentioned, nothing stops you from putting duplicated key values into the array, so you need to be careful, or have the "Dumping" function check for errors like this. Other than that, I think it is a good compromise. This process of using editor-only variables and functions to process and store data into scriptableObjects has been pretty reliable to me, and I have been using it quite frequently with no problems.