How do you do realtime edits to an array in Objective C?

So lets say I am trying to make a cloth simulator work on iOS with unity, the cloth simulator is written in C++. The cloth simulator takes an array of vertices, and does it’s simulation, and rearranges them.

How would I efficiently get that array of vertices in and out of unity? Can I have both C++ and C# in unity referencing the same chunk of memory that holds an array?

anyone?