Change NSView of window programatically

Hi,

I have a toolbar with some buttons. The toolbar is placed in a window with a view controller.

I want to be able to switch from view if I push a button in the toolbar.

This is my code (with everything properly connected)

- (IBAction)Featured:(id)sender {

[self.MainWindow.contentViewaddSubview:FeaturedView];

}

The FeaturedView is connected to the right view controller, and MainWindow is connected to the uppperleft window.

This code doesn't work, can anybody help me please?

Xcode 6 (Newest version), mac os x