There is no public UIContainerView class in Cocoa Touch, but there is a pattern that uses a UIViewController as a container for one or more child view controllers. This pattern is also in the object library of Interface Builder in Xcode with the name Container View.
You can drag a Container View for the object library into a view in a Storyboard scene. This will create a new view in the scene and creates a new view controller object which is connected with the container view by a segue. The view of this new view controller is displayed in the connected view.
The class UIViewController supports nesting of child view controllers. The documentation contains also a section about Implementing a Container View Controller programmatically.
