         PreviewDetail(title: "Large", preferredHeight: 0.0) // 0.0 to get the default height.
     ]
 
-    // MARK: - UIViewController
+}
+
+// MARK: - UIViewController
+
+extension MasterViewController {
 
     override func viewDidLoad() {
         super.viewDidLoad()

        }
    }

    // MARK: - UITableViewDataSource

    override func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return sampleData.count

    }

}
