Xcode 4.6.3 Storyboard Class and Subclass Reference

Xcode 4.6.3 Storyboard Class and Subclass Reference

I this this following stuff:

And I have create a new Objective-C category


And after all on Identify inspector I have defined the Custom Class as
MyScrollView

And when app start on iOS Simulator I received this message:
Unknown class MyScrollView in Interface Builder file.
This approach can be used to implement ViewController, but is not working
to nested classes. Have any solution for this case?