opening a file in unity3d and handling it

I wish to create my own file type to use in my app. I have already linked my file type to the ios app https://developer.apple.com/library/ios/qa/qa1587/_index.html but now i need to tell the app to handle the file, so when i open a file that i sent over email, i open it with my app.

This is where i didn't figure it out yet.

How can i handle the file that i sent via email in unity3d code?