UISplitViewController inside tab bar

You can definitely embed a UISplitViewController inside a UITabBarController. I've done just that for an app I released on the App Store. It has 3 tabs and each one is a split view controller.

Just drag out a tab bar controller into your Storyboard, delete the two controllers it added, then drag out a split view controller. Control drag from the tab bar controller to the split view controller and select the "view controllers" relationship segue.

On Xcode versions less than Xcode 8, you may see black or white bars at the top and bottom of the split view controller in the Interface Builder canvas, but these will not appear when the app is run on a device.

Here is the app running to show the split view embedded inside the tab bar controller on iPhone 6s Plus:

When you put a UISplitViewController inside a UITabBarController and the tab bar is set to be opaque you have an issue where your UISplitViewController content is shifted up the size of the tab bar:

To fix this issue you have to check the Under Opaque Bars checkbox on your UISplitViewController in your storyboard:

And now the UISplitViewController view size is correctly computed:

There is also a problem using this approach in iPhone (>IOS8) where the splitviewcontroller is in collapsed mode. When we push the list view to the details view we cannot hide the tabbarcontroller using the conventional "hidesBottomBarWhenPushed". So I have added the TabBarcontroller as root viewcontroller of a navigationcontroller. Now when I push to details view, I send the message to the root navigation controller and push the view to the details view instance in collapsed mode whereas in regular mode I just push it using showDetailsViewController()