Allow indexed access for non-NSArray collections

NativeScript/runtime/ArgConverter.mm

@@ -883,16 +883,18 @@
 
   ObjCDataWrapper* objcDataWrapper = static_cast<ObjCDataWrapper*>(wrapper);
   id target = objcDataWrapper->Data();
-  if (![target isKindOfClass:[NSArray class]]) {
+  // Treat anything that can report a count and return elements by index as
+  // indexable, not just NSArray (e.g. PHFetchResult, NSOrderedSet).
+  if (![target respondsToSelector:@selector(count)] ||
+      ![target respondsToSelector:@selector(objectAtIndex:)]) {
     return;
   }
 
-  NSArray* array = (NSArray*)target;
-  if (index >= [array count]) {
+  if (index >= [target count]) {
     return;
   }
 
-  id obj = [array objectAtIndex:index];
+  id obj = [target objectAtIndex:index];
 
   std::shared_ptr<Caches> cache = Caches::Get(isolate);
   auto it = cache->Instances.find(obj);

TestRunner/app/tests/ApiTests.js

@@ -22,6 +22,20 @@ describe(module.id, function () {
         expect(res[0].constructor.name).toEqual("NSURL");
     });
 
+    it("indexed access works for non-NSArray indexable collections", function () {
+        // NSOrderedSet is not an NSArray but responds to count + objectAtIndex:,
+        // so obj[i] should resolve the same elements as objectAtIndex(i).
+        const set = NSOrderedSet.orderedSetWithArray(['a', 'b', 'c']);
+        expect(set.count).toBe(3);
+        expect(set[0]).toBe(set.objectAtIndex(0));
+        expect(set[1]).toBe(set.objectAtIndex(1));
+        expect(set[2]).toBe(set.objectAtIndex(2));
+        expect(set[0]).toBe('a');
+        expect(set[2]).toBe('c');
+        // Out-of-range index returns undefined instead of throwing.
+        expect(set[3]).toBeUndefined();
+    });
+
     it("MethodCalledInDealloc", function () {
         expect(function () {
             (function () {