InteractiveMenu2.swift

// MARK: Set Up
extension InteractiveMenu {
    fileprivate func setUpUI() {
        self.translatesAutoresizingMaskIntoConstraints = true //1
        self.frame = CGRect(x: 0, y: 0, width: superview!.frame.size.width, height: superview!.frame.size.height)
        self.addSubview(self.viewBlurBackground)
        self.viewBlurBackground.frame = CGRect(x: 0, y: 0, width: self.frame.size.width, height: self.frame.size.height)
        
        self.addSubview(self.containerView)
        self.containerView.frame = CGRect(x: 0, y: self.frame.size.height - self.configuration.containerViewHeight, width: self.frame.size.width , height: self.totalHeightContainerView)
        
        self.viewInContainer = self.dataSource.interactiveMenuViewInContainerView(interactiveMenu: self)
        viewInContainer.frame = CGRect(x: 0, y: 0, width: self.containerView.frame.size.width , height: self.configuration.containerViewHeight)
        self.containerView.addSubview(viewInContainer)
        viewInContainer.layoutIfNeeded()
        
      //2
        if let scrollableContent = self.dataSource.interactiveMenuViewScrollableContentView(interactiveMenu: self) {
            scrollableContent.addObserver(self, forKeyPath: "contentOffset", options: [.new , .old], context: nil)
            self.panGestureScrollableContent = scrollableContent.gestureRecognizers?.first(where: { rec -> Bool in
                if let _:UIPanGestureRecognizer = rec as? UIPanGestureRecognizer {
                    return true
                }
                return false
            }) as? UIPanGestureRecognizer
            self.scrollableContentView = scrollableContent
            
        }
       
        self.frameOpenPosition = CGRect(x: 0, y: self.frame.size.height - self.configuration.containerViewHeight, width: self.frame.size.width , height: self.totalHeightContainerView)
        self.frameClosedPosition = CGRect(x: 0, y: self.frame.size.height, width: self.frame.size.width , height: self.totalHeightContainerView)
        self.containerView.frame = self.frameClosedPosition
        self.frame = CGRect(x: 0, y: self.frame.size.height, width: self.frame.size.width, height: self.frame.size.height)
     
        let tapGestureBlurView = UITapGestureRecognizer(target: self, action: #selector(blurViewDidTapped))
        self.viewBlurBackground.addGestureRecognizer(tapGestureBlurView)
        
        self.panGestureContainerView = InstantPanGesture(target: self, action: #selector(containerViewPanned(recognizer:))) //3
        self.panGestureContainerView.name = "PanContent"
        self.containerView.addGestureRecognizer(self.panGestureContainerView)
        
        panGestureContainerView.delegate = self
        self.containerView.backgroundColor = self.configuration.containerViewBackgroundColor
    }
  
    //4
    override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) {
        if let key = keyPath , key == "contentOffset" , let scroll = object as? UIScrollView  {
            if scroll.contentOffset.y < 0 {
                scroll.setContentOffset(CGPoint(x: scroll.contentOffset.x, y: 0), animated: false )
            }
        }
    }
    
}