     
     deinit {
         unobserveTitleFrom(viewControllers: viewControllers)
+        unobserveScrollViewDelegate(pageScrollView)
     }
     
     override open func loadView() {

    open override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
        
        if let viewController = object as? UIViewController {
            if keyPath == "title" {
                if let index = viewControllers.index(of: viewController) {
                    pageSegmentedControl.setTitle(viewController.title, forSegmentAt: index)
                }
            }
        }

    }()
    
    /// Delegate
    @objc open weak var delegate: DTPagerControllerDelegate?
    
    /// Preferred height of segmented control bar.
    /// Default value is 44.
