feat: Update package.json to 1.5.0

Implement SubclassSelectorAttribute.UseToStringAsLabel

.github/workflows/package.yaml

@@ -14,7 +14,7 @@ jobs:
     steps:
       # Checkout
       - name: Checkout repository
-        uses: actions/checkout@v2
+        uses: actions/checkout@v4
         with:
           lfs: true
 
@@ -39,7 +39,7 @@ jobs:
 
       # Upload
       - name: Upload .unitypackage
-        uses: actions/upload-artifact@v2
+        uses: actions/upload-artifact@v4
         with:
           name: Unity Package
           path: Build

.github/workflows/release.yaml

@@ -18,7 +18,7 @@ jobs:
     outputs:
       sha: ${{ steps.commit.outputs.sha }}
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
       - name: Output package.json (Before)
         run: cat ${{ env.TARGET_FILE}}
 
@@ -69,7 +69,7 @@ jobs:
     timeout-minutes: 15
     steps:
       - run: echo ${{ needs.update-packagejson.outputs.sha }}
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v4
         with:
           ref: ${{ needs.update-packagejson.outputs.sha }}
 
@@ -97,7 +97,7 @@ jobs:
         working-directory: .
 
       # Store artifacts.
-      - uses: actions/upload-artifact@v2
+      - uses: actions/upload-artifact@v4
         with:
           name: SerializeReference-Extensions.unitypackage
           path: ./Build/SerializeReference-Extensions.unitypackage
@@ -119,7 +119,7 @@ jobs:
           prerelease: false
 
       # Download(All) Artifacts to current directory
-      - uses: actions/download-artifact@v2
+      - uses: actions/download-artifact@v4
       
       # Upload to Releases(unitypackage)
       - uses: actions/upload-release-asset@v1

Assets/Example/Example.cs

@@ -1,4 +1,3 @@
-#if UNITY_2019_3_OR_NEWER
 using System.Collections.Generic;
 using System;
 using UnityEditor;
@@ -42,6 +41,17 @@ public class Grape : Food
 	}
 }
 
+[Serializable]
+[HideInTypeMenu]
+public class Banana : Food
+{
+	public Banana ()
+	{
+		name = "Banana";
+		kcal = 100f;
+	}
+}
+
 public class Example : MonoBehaviour
 {
 
@@ -60,7 +70,8 @@ public class Example : MonoBehaviour
 	[SerializeReference, SubclassSelector]
 	public Food foodTwo = new Peach();
 
-	[SerializeReference, SubclassSelector]
+	// UseToStringAsLabel support on UNITY_2021_3_OR_NEWER
+	[SerializeReference, SubclassSelector(UseToStringAsLabel = true)]
 	public Food foodThree = new Grape();
 
 	[SerializeReference]
@@ -116,5 +127,3 @@ public class AppleDrawer : PropertyDrawer
 	}
 }
 #endif
-
-#endif

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Editor/AdvancedTypePopup.cs

@@ -1,5 +1,4 @@
-#if UNITY_2019_3_OR_NEWER
+using System;
-using System;
 using System.Linq;
 using System.Collections.Generic;
 using UnityEngine;
@@ -138,4 +137,3 @@ namespace MackySoft.SerializeReferenceExtensions.Editor {
 
 	}
 }
-#endif

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Editor/MackySoft.SerializeReferenceExtensions.Editor.asmdef

@@ -12,9 +12,7 @@
     "overrideReferences": false,
     "precompiledReferences": [],
     "autoReferenced": true,
-    "defineConstraints": [
+    "defineConstraints": [],
-        "UNITY_2019_3_OR_NEWER"
-    ],
     "versionDefines": [],
     "noEngineReferences": false
 }

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Editor/ManagedReferenceContextualPropertyMenu.cs

@@ -1,17 +1,20 @@
 // NOTE: managedReferenceValue getter is available only in Unity 2021.3 or later.
 #if UNITY_2021_3_OR_NEWER
+using System;
 using UnityEditor;
 using UnityEngine;
 
 namespace MackySoft.SerializeReferenceExtensions.Editor
 {
-	public static class CopyAndPasteProperty
+	public static class ManagedReferenceContextualPropertyMenu
 	{
 
 		const string kCopiedPropertyPathKey = "SerializeReferenceExtensions.CopiedPropertyPath";
 		const string kClipboardKey = "SerializeReferenceExtensions.CopyAndPasteProperty";
 
 		static readonly GUIContent kPasteContent = new GUIContent("Paste Property");
+		static readonly GUIContent kNewInstanceContent = new GUIContent("New Instance");
+		static readonly GUIContent kResetAndNewInstanceContent = new GUIContent("Reset and New Instance");
 
 		[InitializeOnLoadMethod]
 		static void Initialize ()
@@ -38,6 +41,20 @@ namespace MackySoft.SerializeReferenceExtensions.Editor
 				{
 					menu.AddDisabledItem(kPasteContent);
 				}
+
+				menu.AddSeparator("");
+
+				bool hasInstance = clonedProperty.managedReferenceValue != null;
+				if (hasInstance)
+				{
+					menu.AddItem(kNewInstanceContent, false, NewInstance, clonedProperty);
+					menu.AddItem(kResetAndNewInstanceContent, false, ResetAndNewInstance, clonedProperty);
+				}
+				else
+				{
+					menu.AddDisabledItem(kNewInstanceContent);
+					menu.AddDisabledItem(kResetAndNewInstanceContent);
+				}
 			}
 		}
 
@@ -62,6 +79,29 @@ namespace MackySoft.SerializeReferenceExtensions.Editor
 			JsonUtility.FromJsonOverwrite(json, property.managedReferenceValue);
 			property.serializedObject.ApplyModifiedProperties();
 		}
+
+		static void NewInstance (object customData)
+		{
+			SerializedProperty property = (SerializedProperty)customData;
+			string json = JsonUtility.ToJson(property.managedReferenceValue);
+
+			Undo.RecordObject(property.serializedObject.targetObject, "New Instance");
+			property.managedReferenceValue = JsonUtility.FromJson(json, property.managedReferenceValue.GetType());
+			property.serializedObject.ApplyModifiedProperties();
+
+			Debug.Log($"Create new instance of \"{property.propertyPath}\".");
+		}
+
+		static void ResetAndNewInstance (object customData)
+		{
+			SerializedProperty property = (SerializedProperty)customData;
+
+			Undo.RecordObject(property.serializedObject.targetObject, "Reset and New Instance");
+			property.managedReferenceValue = Activator.CreateInstance(property.managedReferenceValue.GetType());
+			property.serializedObject.ApplyModifiedProperties();
+
+			Debug.Log($"Reset property and created new instance of \"{property.propertyPath}\".");
+		}
 	}
 }
 #endif

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Editor/ManagedReferenceUtility.cs

@@ -1,10 +1,11 @@
-#if UNITY_2019_3_OR_NEWER
+using System;
-using System;
 using System.Reflection;
 using UnityEditor;
 using UnityEngine;
 
-namespace MackySoft.SerializeReferenceExtensions.Editor {
+namespace MackySoft.SerializeReferenceExtensions.Editor
+{
+
 	public static class ManagedReferenceUtility {
 
 		public static object SetManagedReference (this SerializedProperty property,Type type) {
@@ -12,7 +13,7 @@ namespace MackySoft.SerializeReferenceExtensions.Editor {
 
 #if UNITY_2021_3_OR_NEWER
 			// NOTE: managedReferenceValue getter is available only in Unity 2021.3 or later.
-			if (property.managedReferenceValue != null)
+			if ((type != null) && (property.managedReferenceValue != null))
 			{
 				// Restore an previous values from json.
 				string json = JsonUtility.ToJson(property.managedReferenceValue);
@@ -43,4 +44,3 @@ namespace MackySoft.SerializeReferenceExtensions.Editor {
 
 	}
 }
-#endif

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Editor/PropertyDrawerCache.cs

@@ -1,5 +1,4 @@
-#if UNITY_2019_3_OR_NEWER
+using System;
-using System;
 using System.Collections.Generic;
 using UnityEditor;
 using System.Reflection;
@@ -25,9 +24,10 @@ namespace MackySoft.SerializeReferenceExtensions.Editor
 
 		static Type GetCustomPropertyDrawerType (Type type)
 		{
-			foreach (Assembly assembly in AppDomain.CurrentDomain.GetAssemblies())
+			Type[] interfaceTypes = type.GetInterfaces();
-			{
+
-				foreach (Type drawerType in assembly.GetTypes())
+			var types = TypeCache.GetTypesWithAttribute<CustomPropertyDrawer>();
+			foreach (Type drawerType in types)
 			{
 				var customPropertyDrawerAttributes = drawerType.GetCustomAttributes(typeof(CustomPropertyDrawer), true);
 				foreach (CustomPropertyDrawer customPropertyDrawer in customPropertyDrawerAttributes)
@@ -36,10 +36,39 @@ namespace MackySoft.SerializeReferenceExtensions.Editor
 					if (field != null)
 					{
 						var fieldType = field.GetValue(customPropertyDrawer) as Type;
-							if (fieldType != null && fieldType == type)
+						if (fieldType != null)
+						{
+							if (fieldType == type)
 							{
 								return drawerType;
 							}
+							
+							// If the property drawer also allows for being applied to child classes, check if they match
+							var useForChildrenField = customPropertyDrawer.GetType().GetField("m_UseForChildren", BindingFlags.NonPublic | BindingFlags.Instance);
+							if (useForChildrenField != null)
+							{
+								object useForChildrenValue = useForChildrenField.GetValue(customPropertyDrawer);
+								if (useForChildrenValue is bool && (bool)useForChildrenValue)
+								{
+									// Check interfaces
+									if (Array.Exists(interfaceTypes, interfaceType => interfaceType == fieldType))
+									{
+										return drawerType;
+									}
+
+									// Check derived types
+									Type baseType = type.BaseType;
+									while (baseType != null)
+									{
+										if (baseType == fieldType)
+										{
+											return drawerType;
+										}
+
+										baseType = baseType.BaseType;
+									}
+								}
+							}
 						}
 					}
 				}
@@ -49,4 +78,3 @@ namespace MackySoft.SerializeReferenceExtensions.Editor
 
 	}
 }
-#endif

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Editor/SerializedPropertyExtensions.cs

@@ -0,0 +1,29 @@
+using System.Collections.Generic;
+using UnityEditor;
+
+namespace MackySoft.SerializeReferenceExtensions.Editor
+{
+	public static class SerializedPropertyExtensions
+	{
+		public static IEnumerable<SerializedProperty> GetChildProperties (this SerializedProperty parent, int depth = 1)
+		{
+			parent = parent.Copy();
+
+			int depthOfParent = parent.depth;
+			var enumerator = parent.GetEnumerator();
+
+			while (enumerator.MoveNext())
+			{
+				if (enumerator.Current is not SerializedProperty childProperty)
+				{
+					continue;
+				}
+				if (childProperty.depth > (depthOfParent + depth))
+				{
+					continue;
+				}
+				yield return childProperty.Copy();
+			}
+		}
+	}
+}

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Editor/SerializedPropertyExtensions.cs.meta

@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: b934aeca38cb7a24cabd6047fe0e298a
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Editor/SubclassSelectorDrawer.cs

@@ -1,5 +1,4 @@
-#if UNITY_2019_3_OR_NEWER
+using System;
-using System;
 using System.Linq;
 using System.Collections.Generic;
 using UnityEngine;
@@ -22,7 +21,7 @@ namespace MackySoft.SerializeReferenceExtensions.Editor
 		}
 
 		const int k_MaxTypePopupLineCount = 13;
-		static readonly Type k_UnityObjectType = typeof(UnityEngine.Object);
+		
 		static readonly GUIContent k_NullDisplayName = new GUIContent(TypeMenuUtility.k_NullDisplayName);
 		static readonly GUIContent k_IsNotManagedReferenceLabel = new GUIContent("The property type is not manage reference.");
 
@@ -31,48 +30,92 @@ namespace MackySoft.SerializeReferenceExtensions.Editor
 
 		SerializedProperty m_TargetProperty;
 
-		public override void OnGUI (Rect position,SerializedProperty property,GUIContent label) {
+		public override void OnGUI (Rect position, SerializedProperty property, GUIContent label)
+		{
 			EditorGUI.BeginProperty(position, label, property);
 
-			if (property.propertyType == SerializedPropertyType.ManagedReference) {
+			if (property.propertyType == SerializedPropertyType.ManagedReference)
-				// Draw the subclass selector popup.
+			{
-				Rect popupPosition = new Rect(position);
+				// Render label first to avoid label overlap for lists
-				popupPosition.width -= EditorGUIUtility.labelWidth;
+				Rect foldoutLabelRect = new Rect(position);
-				popupPosition.x += EditorGUIUtility.labelWidth;
+				foldoutLabelRect.height = EditorGUIUtility.singleLineHeight;
-				popupPosition.height = EditorGUIUtility.singleLineHeight;
+				foldoutLabelRect = EditorGUI.IndentedRect(foldoutLabelRect);
+				Rect popupPosition = EditorGUI.PrefixLabel(foldoutLabelRect, label);
 
-				if (EditorGUI.DropdownButton(popupPosition,GetTypeName(property),FocusType.Keyboard)) {
+#if UNITY_2021_3_OR_NEWER
+				// Override the label text with the ToString() of the managed reference.
+				var subclassSelectorAttribute = (SubclassSelectorAttribute)attribute;
+				if (subclassSelectorAttribute.UseToStringAsLabel && !property.hasMultipleDifferentValues)
+				{
+					object managedReferenceValue = property.managedReferenceValue;
+					if (managedReferenceValue != null)
+					{
+						label.text = managedReferenceValue.ToString();
+					}
+				}
+#endif
+
+				// Draw the subclass selector popup.
+				if (EditorGUI.DropdownButton(popupPosition, GetTypeName(property), FocusType.Keyboard))
+				{
 					TypePopupCache popup = GetTypePopup(property);
 					m_TargetProperty = property;
 					popup.TypePopup.Show(popupPosition);
 				}
 
+				// Draw the foldout.
+				if (!string.IsNullOrEmpty(property.managedReferenceFullTypename))
+				{
+					Rect foldoutRect = new Rect(position);
+					foldoutRect.height = EditorGUIUtility.singleLineHeight;
+
+#if UNITY_2022_2
+					// NOTE: Position x must be adjusted.
+					// FIXME: Is there a more essential solution...?
+					foldoutRect.x -= 12;
+#endif
+
+					property.isExpanded = EditorGUI.Foldout(foldoutRect, property.isExpanded, GUIContent.none, true);
+				}
+
+				// Draw property if expanded.
+				if (property.isExpanded)
+				{
+					using (new EditorGUI.IndentLevelScope())
+					{
 						// Check if a custom property drawer exists for this type.
 						PropertyDrawer customDrawer = GetCustomPropertyDrawer(property);
 						if (customDrawer != null)
 						{
 							// Draw the property with custom property drawer.
-					Rect foldoutRect = new Rect(position);
-					foldoutRect.height = EditorGUIUtility.singleLineHeight;
-					property.isExpanded = EditorGUI.Foldout(foldoutRect, property.isExpanded, label, true);
-					
-					if (property.isExpanded)
-					{
-						using (new EditorGUI.IndentLevelScope())
-						{
 							Rect indentedRect = position;
 							float foldoutDifference = EditorGUIUtility.singleLineHeight + EditorGUIUtility.standardVerticalSpacing;
 							indentedRect.height = customDrawer.GetPropertyHeight(property, label);
 							indentedRect.y += foldoutDifference;
 							customDrawer.OnGUI(indentedRect, property, label);
 						}
+						else
+						{
+							// Draw the properties of the child elements.
+							// NOTE: In the following code, since the foldout layout isn't working properly, I'll iterate through the properties of the child elements myself.
+							// EditorGUI.PropertyField(position, property, GUIContent.none, true);
+
+							Rect childPosition = position;
+							childPosition.y += EditorGUIUtility.singleLineHeight + EditorGUIUtility.standardVerticalSpacing;
+							foreach (SerializedProperty childProperty in property.GetChildProperties())
+							{
+								float height = EditorGUI.GetPropertyHeight(childProperty, new GUIContent(childProperty.displayName, childProperty.tooltip), true);
+								childPosition.height = height;
+								EditorGUI.PropertyField(childPosition, childProperty, true);
+
+								childPosition.y += height + EditorGUIUtility.standardVerticalSpacing;
+							}
+						}
+					}
 				}
 			}
 			else
 			{
-					EditorGUI.PropertyField(position, property, label, true);
-				}
-			} else {
 				EditorGUI.LabelField(position, label, k_IsNotManagedReferenceLabel);
 			}
 
@@ -98,13 +141,7 @@ namespace MackySoft.SerializeReferenceExtensions.Editor
 
 				Type baseType = ManagedReferenceUtility.GetType(managedReferenceFieldTypename);
 				var popup = new AdvancedTypePopup(
-					TypeCache.GetTypesDerivedFrom(baseType).Append(baseType).Where(p =>
+					TypeMenuUtility.GetTypes(baseType),
-						(p.IsPublic || p.IsNestedPublic) &&
-						!p.IsAbstract &&
-						!p.IsGenericType &&
-						!k_UnityObjectType.IsAssignableFrom(p) &&
-						Attribute.IsDefined(p,typeof(SerializableAttribute))
-					),
 					k_MaxTypePopupLineCount,
 					state
 				);
@@ -115,7 +152,6 @@ namespace MackySoft.SerializeReferenceExtensions.Editor
 					foreach (var targetObject in m_TargetProperty.serializedObject.targetObjects) {
 						SerializedObject individualObject = new SerializedObject(targetObject);
 						SerializedProperty individualProperty = individualObject.FindProperty(m_TargetProperty.propertyPath);
-
 						object obj = individualProperty.SetManagedReference(type);
 						individualProperty.isExpanded = (obj != null);
 
@@ -175,4 +211,3 @@ namespace MackySoft.SerializeReferenceExtensions.Editor
 
 	}
 }
-#endif

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Editor/TypeMenuUtility.cs

@@ -1,12 +1,25 @@
-#if UNITY_2019_3_OR_NEWER
+using System;
-using System;
 using System.Linq;
 using System.Collections.Generic;
+using UnityEditor;
 
 namespace MackySoft.SerializeReferenceExtensions.Editor {
 	public static class TypeMenuUtility {
 
 		public const string k_NullDisplayName = "<null>";
+		static readonly Type k_UnityObjectType = typeof(UnityEngine.Object);
+
+		public static IEnumerable<Type> GetTypes (Type baseType)
+		{
+			return TypeCache.GetTypesDerivedFrom(baseType).Append(baseType).Where(p =>
+				(p.IsPublic || p.IsNestedPublic || p.IsNestedPrivate) &&
+				!p.IsAbstract &&
+				!p.IsGenericType &&
+				!k_UnityObjectType.IsAssignableFrom(p) &&
+				Attribute.IsDefined(p, typeof(SerializableAttribute)) &&
+				!Attribute.IsDefined(p, typeof(HideInTypeMenuAttribute))
+			);
+		}
 
 		public static AddTypeMenuAttribute GetAttribute (Type type) {
 			return Attribute.GetCustomAttribute(type,typeof(AddTypeMenuAttribute)) as AddTypeMenuAttribute;
@@ -42,4 +55,3 @@ namespace MackySoft.SerializeReferenceExtensions.Editor {
 
 	}
 }
-#endif

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Runtime/AddTypeMenuAttribute.cs

@@ -1,6 +1,4 @@
-#if UNITY_2019_3_OR_NEWER
+using System;
-
-using System;
 	
 /// <summary>
 /// An attribute that overrides the name of the type displayed in the SubclassSelector popup.
@@ -35,4 +33,3 @@ public sealed class AddTypeMenuAttribute : Attribute {
 	}
 
 }
-#endif

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Runtime/HideInTypeMenuAttribute.cs

@@ -0,0 +1,9 @@
+using System;
+
+/// <summary>
+/// An attribute that hides the type in the SubclassSelector.
+/// </summary>
+[AttributeUsage(AttributeTargets.Class | AttributeTargets.Struct | AttributeTargets.Enum | AttributeTargets.Interface, AllowMultiple = false, Inherited = false)]
+public sealed class HideInTypeMenuAttribute : Attribute {
+
+}

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Runtime/HideInTypeMenuAttribute.cs.meta

@@ -0,0 +1,11 @@
+fileFormatVersion: 2
+guid: 9f48f5d86a108b94a9c26381f5ce678c
+MonoImporter:
+  externalObjects: {}
+  serializedVersion: 2
+  defaultReferences: []
+  executionOrder: 0
+  icon: {instanceID: 0}
+  userData: 
+  assetBundleName: 
+  assetBundleVariant: 

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Runtime/MackySoft.SerializeReferenceExtensions.asmdef

@@ -8,9 +8,7 @@
     "overrideReferences": false,
     "precompiledReferences": [],
     "autoReferenced": true,
-    "defineConstraints": [
+    "defineConstraints": [],
-        "UNITY_2019_3_OR_NEWER"
-    ],
     "versionDefines": [],
     "noEngineReferences": false
 }

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/Runtime/SubclassSelectorAttribute.cs

@@ -1,12 +1,16 @@
-#if UNITY_2019_3_OR_NEWER
+using System;
-using System;
 using UnityEngine;
 
 /// <summary>
 /// Attribute to specify the type of the field serialized by the SerializeReference attribute in the inspector.
 /// </summary>
 [AttributeUsage(AttributeTargets.Field, AllowMultiple = false)]
-public sealed class SubclassSelectorAttribute : PropertyAttribute {
+public sealed class SubclassSelectorAttribute : PropertyAttribute
+{
+
+#if UNITY_2021_3_OR_NEWER
+	// NOTE: Use managedReferenceValue getter to invoke instance method in SubclassSelectorDrawer.
+	public bool UseToStringAsLabel { get; set; }
+#endif
 
 }
-#endif

Assets/MackySoft/MackySoft.SerializeReferenceExtensions/package.json

@@ -2,7 +2,7 @@
 	"name": "com.mackysoft.serializereference-extensions",
 	"displayName": "SerializeReference Extensions",
 	"author": { "name": "MackySoft", "url": "https://github.com/mackysoft" },
-	"version": "1.2.1",
+	"version": "1.5.0",
 	"unity": "2021.3",
 	"description": "Provide popup to specify the type of the field serialized by the [SerializeReference] attribute in the inspector.",
 	"keywords": [ "SerializeReference", "Editor" ],

Packages/manifest.json

@@ -1,7 +1,7 @@
 {
   "dependencies": {
-    "com.unity.ide.rider": "3.0.24",
+    "com.unity.ide.rider": "3.0.28",
-    "com.unity.ide.visualstudio": "2.0.18",
+    "com.unity.ide.visualstudio": "2.0.22",
     "com.unity.ide.vscode": "1.2.5",
     "com.unity.test-framework": "1.1.33",
     "com.unity.modules.ai": "1.0.0",

Packages/packages-lock.json

@@ -8,7 +8,7 @@
       "url": "https://packages.unity.com"
     },
     "com.unity.ide.rider": {
-      "version": "3.0.24",
+      "version": "3.0.28",
       "depth": 0,
       "source": "registry",
       "dependencies": {
@@ -17,7 +17,7 @@
       "url": "https://packages.unity.com"
     },
     "com.unity.ide.visualstudio": {
-      "version": "2.0.18",
+      "version": "2.0.22",
       "depth": 0,
       "source": "registry",
       "dependencies": {

README.md

@@ -15,12 +15,19 @@ The `SubclassSelector` attribute allows you to easily set subclasses of those ab
 - Easily set subclass by popup.
 - **[New]** Type finding by fuzzy finder.
 - **[New]** Override the type name and path by the `AddTypeMenu` attribute.
-- **[New]** Restore values of previous object from JSON when subclass is changed.
-- **[New]** Copy & Paste the subclass properties.
 - **[New]** Available `CustomPropertyDrawer` for subclasses.
+- **[New]** Restore values of previous object from JSON when subclass is changed. (required Unity 2021.3 or later)
+- **[New]** Copy & Paste the subclass properties. (required Unity 2021.3 or later)
+- **[New]** Clear & reset the subclass properties. (required Unity 2021.3 or later)
+
+> See below for the reason for the limitation of versions less than Unity 2021.3.
+> 
+> https://blog.unity.com/engine-platform/serializereference-improvements-in-unity-2021-lts
 
 ## 📥 Installation
 
+#### Install via `.unitypackage`
+
 Download any version from releases.
 
 Releases: https://github.com/mackysoft/Unity-SerializeReferenceExtensions/releases
@@ -29,10 +36,17 @@ Releases: https://github.com/mackysoft/Unity-SerializeReferenceExtensions/releas
 
 Or, you can add this package by opening PackageManager and entering
 
-`https://github.com/mackysoft/Unity-SerializeReferenceExtensions.git?path=Assets/MackySoft/MackySoft.SerializeReferenceExtensions`
+```
+https://github.com/mackysoft/Unity-SerializeReferenceExtensions.git?path=Assets/MackySoft/MackySoft.SerializeReferenceExtensions
+```
 
 from the `Add package from git URL` option.
 
+If you are specifying a version, enter `#{VERSION}` at the end, as shown below.
+
+```
+https://github.com/mackysoft/Unity-SerializeReferenceExtensions.git?path=Assets/MackySoft/MackySoft.SerializeReferenceExtensions#1.1.9
+```
 
 #### Install via Open UPM
 
@@ -125,7 +139,7 @@ public struct StructCommand : ICommand {
 
 The `SubclassSelector` attribute supports types that meet the following conditions.
 
-- Public
+- Public or nested private
 - Not abstract
 - Not generic
 - Not unity object