Added some backwards compatability support

Author: Lachee

Editor/Lachee.Utilities.Editor.asmdef

@@ -1,18 +1,12 @@
 {
     "name": "Lachee.Utilities.Editor",
-    "rootNamespace": "",
     "references": [
-        "GUID:aa08d19502347e74bb216b7098a7c7c9"
+        "Lachee.Utilities.Runtime"
     ],
+    "optionalUnityReferences": [],
     "includePlatforms": [
         "Editor"
     ],
     "excludePlatforms": [],
-    "allowUnsafeCode": false,
-    "overrideReferences": false,
-    "precompiledReferences": [],
-    "autoReferenced": true,
-    "defineConstraints": [],
-    "versionDefines": [],
-    "noEngineReferences": false
+    "allowUnsafeCode": false
 }

Runtime/Utilities/Linq.cs

@@ -25,7 +25,7 @@ public static class Linq
         public static TSource Random<TSource>(this IEnumerable<TSource> source, int upperBounds = int.MaxValue)
         {
             // The enumerator to iterate over
-            using var enumerator = source.GetEnumerator();
+            var enumerator = source.GetEnumerator();
 
             // The number of items we have found.
             // If we loop over, then we will reset the counter to a random number within this range.

Runtime/Utilities/Serialization/TextureSurrogate.cs

@@ -19,8 +19,11 @@ public class Texture2DSurrogate : ISerializationSurrogate
         public void GetObjectData(object obj, SerializationInfo info, StreamingContext context)
         {
             Texture2D texture = (Texture2D)obj;
+
+#if UNITY_2018_3_OR_NEWER
             if (!texture.isReadable)
                 throw new System.NotSupportedException("Textures must be readable to serialize");
+#endif
 
             var data = texture.GetRawTextureData();
             info.AddValue(ValueName, texture.name);
@@ -36,13 +39,23 @@ public void GetObjectData(object obj, SerializationInfo info, StreamingContext c
 
         public object SetObjectData(object obj, SerializationInfo info, StreamingContext context, ISurrogateSelector selector)
         {
+#if UNITY_2021_OR_NEWER
             Texture2D texture = new Texture2D(
                 info.GetInt32(ValueWidth),
                 info.GetInt32(ValueHeight),
                 (TextureFormat) info.GetInt32(ValueFormat),
                 info.GetInt32(ValueMipmap),
                 false
             );
+#else
+            Texture2D texture = new Texture2D(
+                info.GetInt32(ValueWidth),
+                info.GetInt32(ValueHeight),
+                (TextureFormat)info.GetInt32(ValueFormat),
+                true,
+                false
+            );
+#endif
 
             texture.filterMode = (FilterMode) info.GetInt32(ValueFilter);
             texture.wrapMode = (TextureWrapMode) info.GetInt32(ValueWrap);

Runtime/Utilities/Singleton.cs

@@ -23,13 +23,14 @@ public abstract class Singleton<T> : MonoBehaviour where T : Singleton<T>
         internal static T _instance;
         private static bool _isquitting = false;
 
+#if UNITY_2019_2_OR_NEWER
         [RuntimeInitializeOnLoadMethod(RuntimeInitializeLoadType.SubsystemRegistration)]
         static void Init()
         {
             _instance = null;
             _isquitting = false;
         }
-
+#endif
 
         /// <summary>
         /// The current type that belongs to this singleton. Alias of <code>typeof(T)</code>.
@@ -65,13 +66,13 @@ public static T instance
                     //We do not have one available, lets create it as a new gameobject.
                     if (Application.isPlaying)
                     {
-                        #if !DONT_CREATE_SINGLETONS
+#if !DONT_CREATE_SINGLETONS
                         GameObject obj = new GameObject($"[ {type} INSTANCE ]");
                         _instance = obj.AddComponent<T>();
                         Debug.LogWarning("Singleton " + type + " does not exist. A new instance has been created instead.", _instance);
-                        #else
+#else
                         Debug.LogError($"Singleton {type} cannot be created because DONT_CREATE_SINGLETONS is defined");
-                        #endif
+#endif
                     } 
                     else 
                     {
@@ -170,9 +171,9 @@ protected virtual void OnApplicationQuit()
         /// </summary>
         protected virtual void Awake()
         {
-            #if UNITY_EDITOR
+#if UNITY_EDITOR
             if (Application.isPlaying)
-            #endif
+#endif
             if (dontDestroyOnLoad)
                 DontDestroyOnLoad(gameObject);
         }

package.json

@@ -1,6 +1,6 @@
 {
   "name": "com.lachee.utilities",
-  "version": "1.3.7",
+  "version": "1.3.8",
   "displayName": "Lachee's Utilities",
   "description": "Bunch of utility functionality",
   "unity": "2019.1",