Convenience extension on UIViewController for containing child view controllers.

ViewControllerContainment.swift

extension UIViewController {
    
    /**
     Convenience function to add a child view controller to self.
     
     This will send the proper notifications to the child view controller
     and add the child view controller's view to `self.view`.
     
     - parameter child: The view controller that should be contained in `self`.
     */
    func addContainedChildViewController(child: UIViewController) {
        addContainedChildViewController(child, inView: view)
    }
    
    /**
     Convenience function to add a child view controller to self.
     
     This will send the proper notifications to the child view controller
     and add the child view controller's view to the provided `parentView`.
     
     - parameter child: The view controller that should be contained in `self`.
     - parameter parentView: The view in which to add the child's view.
     */
    func addContainedChildViewController(child: UIViewController, inView parentView: UIView) {
        addChildViewController(child)
        parentView.addSubview(child.view)
        child.didMoveToParentViewController(self)
    }
    
    /**
     Convenience function to break containment with a parent view controller.
     
     Calling this on a child/contained view controller will call the
     proper methods to have it removed. It will send the proper notifications
     to the child view controller.
    */
    func breakContainment() {
        willMoveToParentViewController(nil)
        view.removeFromSuperview()
        removeFromParentViewController()
    }
}