[mention|SG5WkCwknn0B4Xixxrc3gw==] Please edit your post to use Code Tags
I don’t think that NSUserDefaults maps to PlayerPrefs.
You might want to send a message from XCode to Unity using UnitySendMessage, which will send a message to a gameobject in Unity.
More details can be found here: Unity - Manual: Native plug-ins for iOS