Convert nlohmann::json to NSDictionary

Summary: T46426056: Add utility to convert nlohmann::json to NSDictionary. Use same in instagram logging module.

Differential Revision: D16798341

fbshipit-source-id: 88923fcbcd1ffbed5a468cee4ba2f9482ba81a97

iOS/FlipperKit/FBCxxUtils/FBCxxNlohmannJSONConvert.h

@@ -0,0 +1,13 @@
+// Copyright 2004-present Facebook. All Rights Reserved.
+#pragma once
+
+#import <Foundation/Foundation.h>
+
+#include <nlohmann/json.hpp>
+
+namespace facebook {
+namespace cxxutils {
+using json = nlohmann::json;
+NSDictionary<NSString *, id> *convertNlohmannJSONToNSDictionary(const json &input);
+}
+}