Writing a Custom SceneReferenceHandler

You may want to access instances of your own components from your Actions at runtime. One way of doing this is with a custom SceneReferenceHandler. You can only reference types that inherit Unity.Object, so they can be serialized.

Custom SceneReferenceHandlers require three pieces of data:

1. A type to reference; such as your own MonoBehaviour component
2. A SceneReferenceLookup for this type
3. The actual SceneReferenceHandler, which you will add to the EventBehaviour

1. The Type to Reference

For this example, we will use a custom component ‘MyCustomComponent’:

public class MyComponent : MonoBehaviour { }

2. SceneReferenceLookup

SceneReferenceLookup is a generic class that allows you to wrap a Serializable Dictionary for a given Type, such that it can be stored for use in the SceneReferenceHandler. This is done simply by implementing a class that inherits SceneReferenceLookup, with your component as the generic type. Note: You must add the System.Serializable Attribute to this class.

[Serializable] 
public class MyComponentLookup : SceneReferenceLookup<MyComponent> { }

3. SceneReferenceHandler

With the above two constituents, you can now implement your own SceneReferenceHandler. As this is a MonoBehaviour, it must exist in a file with the same name as the class, or Unity will not serialize it.

public class MyComponentReferenceHandler : SceneReferenceHandler<MyComponentLookup, MyComponent> { }

You can then add MyComponentReferenceHandler to your EventBehaviour, and you will be able to assign instances of MyComponent to it in the inspector.