The delegate you want to receive split view controller messages.
The split view controller uses its delegate to manage the showing and hiding of related view controllers. For more information about the methods you can implement in your delegate, see
Customizing the Split View Behavior
UISplitViewControllerDelegate protocol defines methods that allow you to manage changes to a split view interface. Use the methods of this protocol to respond to changes in the current display mode and to the current interface orientation. When the split view interface collapses and expands, or when a new view controller is added to the interface, you can also use these methods to configure the child view controllers appropriately.