             .drive(onNext: { offsetY in
                 self.topImageView.frame.origin.y = offsetY
                 self.topImageView.frame.size.height = 200 - offsetY
-//                self.topImageView.snp.updateConstraints({ (make) in
-//                    make.top.equalToSuperview().offset(offsetY)
-//                    make.height.equalTo(200 - offsetY)
-//                })
             })
         .addDisposableTo(disposeBag)
         

        imgLabel.font = UIFont.systemFont(ofSize: 10)
        imgLabel.textAlignment = .right
        imgLabel.textColor = UIColor.white
        
        scrollView.addSubview(topImageView)
        scrollView.addSubview(maskImageView)
        scrollView.addSubview(titleLabel)
        scrollView.addSubview(imgLabel)

//        topImageView.snp.makeConstraints { (make) in
//            make.leading.trailing.equalToSuperview()
//            make.top.equalToSuperview().offset(0)
//            make.width.equalTo(screenW)
//            make.height.equalTo(200)
//        }
//
//        maskImageView.snp.makeConstraints { (make) in
//            make.bottom.equalTo(topImageView)
//            make.leading.trailing.equalToSuperview()
//            make.height.equalTo(100)
//        }
//
//        titleLabel.snp.makeConstraints { (make) in
//            make.leading.equalToSuperview().offset(15)
//            make.trailing.equalToSuperview().offset(-15)
//            make.bottom.equalTo(topImageView).offset(-25)
//        }
//
//        imgLabel.snp.makeConstraints { (make) in
//            make.leading.equalToSuperview().offset(15)
//            make.trailing.equalToSuperview().offset(-15)
//            make.bottom.equalTo(topImageView).offset(-5)
//        }
        topImageView.frame = CGRect.init(x: 0, y: 0, width: screenW, height: 200)
        maskImageView.frame = CGRect.init(x: 0, y: 100, width: screenW, height: 100)
        titleLabel.frame =  CGRect.init(x: 15, y: 150, width: screenW - 30, height: 26)
        imgLabel.frame = CGRect.init(x: 15, y: 180, width: screenW - 30, height: 16)
    }
    
    required init?(coder: NSCoder) {
        fatalError("")
    }
    
    // MARK: - View

        super.init(frame: CGRect.zero, configuration: config)
        setupUI()
        
        self.navigationDelegate = self
        
        // 监听偏移量
        offset.asDriver()
            .filter { $0.y < 0 }
