Add dictionary extension methods and replace ConcurrentDictionary with Dictionary in ImageLoader for older Unity version support

Author: IvanMurzak

Assets/_PackageRoot/Runtime/Extensions.cs

@@ -0,0 +1,23 @@
+using System;
+using System.Collections.Generic;
+
+namespace Extensions.Unity.ImageLoader
+{
+    static class Extensions
+    {
+        public static void AddOrUpdate<TKey, TValue>(this Dictionary<TKey, TValue> dictionary, TKey key, TValue addValue, Func<TKey, TValue, TValue> updateValueFactory)
+        {
+            lock (dictionary)
+            {
+                if (dictionary.TryGetValue(key, out var existingValue))
+                {
+                    dictionary[key] = updateValueFactory(key, existingValue);
+                }
+                else
+                {
+                    dictionary[key] = addValue;
+                }
+            }
+        }
+    }
+}

Assets/_PackageRoot/Runtime/Extensions.cs.meta

@@ -7,7 +7,7 @@ namespace Extensions.Unity.ImageLoader
 {
     public static partial class ImageLoader
     {
-        internal static volatile ConcurrentDictionary<string, Sprite> memorySpriteCache = new ConcurrentDictionary<string, Sprite>();
+        internal static volatile Dictionary<string, Sprite> memorySpriteCache = new Dictionary<string, Sprite>();
 
 #if UNITY_EDITOR
         [UnityEditor.InitializeOnEnterPlayMode]

Assets/_PackageRoot/Runtime/ImageLoader.MemoryCache.cs

@@ -1,12 +1,11 @@
 using System;
-using System.Collections.Concurrent;
 using System.Collections.Generic;
 
 namespace Extensions.Unity.ImageLoader
 {
     public partial class Reference<T> : IDisposable
     {
-        private volatile static ConcurrentDictionary<string, int> referenceCounters = new ConcurrentDictionary<string, int>();
+        private volatile static Dictionary<string, int> referenceCounters = new Dictionary<string, int>();
         internal static void Clear()
         {
             lock (referenceCounters) referenceCounters.Clear();
@@ -15,7 +14,7 @@ internal static void Clear()
         internal static bool Clear(string url)
         {
             var result = false;
-            lock (referenceCounters) result = referenceCounters.Remove(url, out var _);
+            lock (referenceCounters) result = referenceCounters.Remove(url);
             EventOnClearUrl?.Invoke(url);
             return result;
         }