Get actual object of SerializedProperty

SerializedPropertyExtensions.cs

using System;
using System.Collections;
using System.Collections.Generic;
using System.Reflection;
using System.Text.RegularExpressions;
using UnityEditor;
using UnityEngine;
using UnityEngine.Assertions;

public static class SerializedPropertyExtensions
{
    private static readonly Dictionary<(Type, string fieldName), FieldInfo> _fieldInfoDictionary = new();
    private static readonly Regex ArrayDataRegex = new(@"data\[(\d+)\]");

    public static object GetActualObject(this SerializedProperty property)
    {
        var serializedObject = property.serializedObject;
        if (serializedObject == null)
        {
            return null;
        }

        object targetObject = serializedObject.targetObject;
        foreach (var fieldName in property.propertyPath.Split('.'))
        {
            if (targetObject == null)
            {
                break;
            }

            var type = targetObject.GetType();

            // Array/ListのpropertyPathは
            // "Array.data[n]" となっている
            if (targetObject is IList list)
            {
                if (fieldName == "Array")
                {
                    continue;
                }

                var match = ArrayDataRegex.Match(fieldName);
                if (!match.Success)
                {
                    Debug.LogWarning($"Invalid propertyPath: {property.propertyPath}");
                    return null;
                }

                var index = Convert.ToInt32(match.Groups[1].Value);
                targetObject = list[index];
                continue;
            }


            var key = (type, fieldName);
            if (!_fieldInfoDictionary.TryGetValue(key, out var fi))
            {
                fi = type.GetField(fieldName, BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic);
                _fieldInfoDictionary[key] = fi;
                Assert.IsNotNull(fi, $"FieldInfo is null. Type: {type}, FieldName: {fieldName}");
            }

            targetObject = fi.GetValue(targetObject);
        }


        return targetObject;
    }
}