ISerializationCallbackReceiver

Description

Interface to receive callbacks upon serialization and deserialization.

Unity's serializer is able to serialize most datatypes, but not all of them. In these cases, there are two callbacks available for you to manually process these datatypes so that Unity can serialize and deserialise them.

Care needs to be taken whilst within these callbacks, as Unity's serializer runs on a different thread to most of the Unity API. It's advisable to only process the manipulation of datatypes, keeping the processing burden as low as possible.

Serialization can occur during all kinds of operations. For example, when using Instantiate() to clone an object, Unity serializes and deserializes the original object in order to find internal references to the original object, so that it can replace them with references to the cloned object. In this situation, you can also employ the callbacks to update any internal references using types that Unity can't serialize.

The callback interface only works with classes. It does not work with structs.

Notes:
- The order of callbacks is undefined for fields marked with [SerializeReference] that reference managed instances with [SerializeReference] fields. In this case, use the callbacks for the main scripting object.

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

public class SerializationCallbackScript : MonoBehaviour, ISerializationCallbackReceiver
{
    public List<int> _keys = new List<int> { 3, 4, 5 };
    public List<string> _values = new List<string> { "I", "Love", "Unity" };

    //Unity doesn't know how to serialize a Dictionary
    public Dictionary<int, string>  _myDictionary = new Dictionary<int, string>();

    public void OnBeforeSerialize()
    {
        _keys.Clear();
        _values.Clear();

        foreach (var kvp in _myDictionary)
        {
            _keys.Add(kvp.Key);
            _values.Add(kvp.Value);
        }
    }

    public void OnAfterDeserialize()
    {
        _myDictionary = new Dictionary<int, string>();

        for (int i = 0; i != Math.Min(_keys.Count, _values.Count); i++)
            _myDictionary.Add(_keys[i], _values[i]);
    }

    void OnGUI()
    {
        foreach (var kvp in _myDictionary)
            GUILayout.Label("Key: " + kvp.Key + " value: " + kvp.Value);
    }
}

Public Methods