DStack DSTabsViewController Extensions for working with constraints DSTabsViewController class TabsViewController: DSTabsViewController<HeaderView> { init() { super.init(viewControllers: [ UIViewController(), UIViewController() ]) } required init?(coder aDecoder: NSCoder) { fatalError('init(coder:) has not been implemented') } } Demo (Click for watching) Extensions for working with constraints let stackView = UIStackView() .addInRootView(view) .setTopAnchor(anchor: topLayoutGuide.bottomAnchor, marge: 10) .setRightAnchor(anchor: view.rightAnchor, marge: 10) .setBottomAnchor(anchor: bottomLayoutGuide.topAnchor, marge: 10) .setLeftAnchor(anchor: view.leftAnchor, marge: 10) let side: CGFloat = 70 label1.addInRootView(stackView) .setSize(width: side, height: side) .setTopAlignment() .setCenterX() Demo