fix usearch for iOS

Author: amakropoulos

Runtime/RAG/usearch/NativeMethods.cs

@@ -11,7 +11,11 @@ namespace Cloud.Unum.USearch
 {
     public static class NativeMethods
     {
+#if UNITY_IOS
+        private const string LibraryName = "__Internal";
+#else
         private const string LibraryName = "libusearch_c";
+#endif
 
         [DllImport(LibraryName, CallingConvention = CallingConvention.Cdecl)]
         public static extern usearch_index_t usearch_init(ref IndexOptions options, out usearch_error_t error);

Runtime/RAG/usearch/USearchIndex.cs

@@ -318,17 +318,10 @@ private int Search<T>(T[] queryVector, int count, out ulong[] keys, out float[]
                 }
                 else
                 {
-                    if (Application.platform == RuntimePlatform.Android)
+                    lock (filterLock)
                     {
-                        lock (filterLock)
-                        {
-                            FilterFunction = filter;
-                            matches = checked((int)usearch_filtered_search(this._index, queryVectorPtr, scalarKind, (UIntPtr)count, StaticFilter, IntPtr.Zero, keys, distances, out error));
-                        }
-                    }
-                    else
-                    {
-                        matches = checked((int)usearch_filtered_search(this._index, queryVectorPtr, scalarKind, (UIntPtr)count, (int key, IntPtr state) => filter(key), IntPtr.Zero, keys, distances, out error));
+                        FilterFunction = filter;
+                        matches = checked((int)usearch_filtered_search(this._index, queryVectorPtr, scalarKind, (UIntPtr)count, StaticFilter, IntPtr.Zero, keys, distances, out error));
                     }
                 }
                 HandleError(error);