New Framework: for OSX?

I think I’m quiet experienced with Xojo but very confused about the new framework. I copied the example from into a new method in a new project (Xojo pro 2015.1, compiled for and on OSX):

Using Xojo.Core
Using Xojo.IO 

The error-code I get is:
There is no class with this name
Using Xojo.IO

So my question: Is only for iOS? Or what is the problem?

yes, exactly. Have a look at the docs:

The desktop classes will adopt mor and more new framework features, but this will take some time.