Any other way aside UnitySendMessage?

I want to develop ios plugin for unity. But in document mention only one way to communicate from ios to unity with UnitySendMessage There is a flaw in this function. I don't know what happen if the GameObjectName has multiple object with same name. So I don't want to use it Are there any other function or way to do, like UnitySendMessage with using InstanceID of object instead? Or direct event delegate of UnitySendMessage? Or passing function pointer to call in C directly? Thank you very much