struct AppModel {
    let appIcon: String
    let appName: String
    let appUseTime: String
}

// ChallengeViewController
extension ChallengeViewController: UIScrollViewDelegate {
    
    func scrollViewWillBeginDecelerating(_ scrollView: UIScrollView) {
        if scrollView.panGestureRecognizer.translation(in: scrollView).y < 0 {
            UIView.animate(withDuration: 0.3, animations: {
                self.navigationBar.alpha = 0
            })
        } else {
            UIView.animate(withDuration: 0.3, animations: {
                self.navigationBar.alpha = 1
            })
        }
    }
}

self.snp.makeConstraints {
         $0.height.equalTo(63.adjustedHeight)
      }
}