I've seen apps that place a colorful border or image around split view controls. To me, it looks like these apps add an image to the window, and then resize the split to be slight smaller then the screen.
How to change background graphic/theme in splitview on ipad?
http://www.iosinspires.me/category/appinterfaces/post/446/Timix_Interface.html
I've tried to manually resize the UISplitView by changing it Frame (UISplitViewwill resizes to cover screen), or by setting a border width, with a clear color (border is ignored when clear).
Does it look like the two examples used split views? Is that the correct control to use for this look?