C# - How to stop unity destroying custom objects on exiting playmode?

Questions & Answers
1

I’m using [ExecuteInEditMode] to run my script in the editor - the script works fine and creates some objects from a custom class that I’ve written.

I was surprised to discover that all of my custom objects are destroyed when entering or exiting playmode leading to problems for me with null references in my script.

Is there any way to prevent objects being destroyed when entering or exiting playmode? Unity seems to flush everything from memory. My custom class derives from ScriptableObject but using DontDestroyOnLoad(this) doesn’t seem to make any difference.

2

I am not sure if it will help you but you can detect when your are exiting playmode with this:

public void OnApplicationQuit()
{
if (Application.isEditor)
IsEditorStopping = true;

}

Also, when you want to use DontDestroyOnLoad, don`t use the script, use the object like this:
DontDestroyOnLoad(this.gameObject)

3

Answering my own question here as the cause to this problem was human error!

I forgot to put [System.Serializable] before one of my custom class declarations (I can only blame late night sleep deprived coding) and now that it’s been added, Unity is holding onto all the data that I need.