How to get the file data of a file on iOS?

Prime31’s SocialNetworking plugin example doesn’t cover this. I want to post an image from a known location to facebook using Facebook.postImage(bytes, etc) however I cannot figure out how to get the “bytes” that facebook is looking for. I have the file saved on the iOS device. I need byte from file path.

byte bytes = File.ReadAllBytes(pathToFile);