Is it possible to use UISplitViewController in a Mac app?
No, it's part of UIKit and thus not available on Mac. You can use NSSplitView if you need a view with multiple panes, but it has a very different API.
Besides, the most significant feature of UISplitViewController (handling auto-rotation and hiding the master view in portrait mode) doesn't make much sense in a Mac app, as the screen never rotates.