                 ThemeHUD.hideActivityIndicator()
                 if self?.model?.count == 0 {
                     self?.defaultView.hidden = false
+                    self?.goTopButton.hidden = true
                 }else {
                     self?.defaultView.hidden = true
+                    self?.goTopButton.hidden = false
                     self?.tableView.reloadData()
                     self?.scrollToToday(false)
                 }
             })
         }
     }
+    /// 距当前时间最近的一节未上课程下标
     var recentlyCourseIndexPath: NSIndexPath?
     /// 当前显示年月（用于TitleView显示）
     var currentDate: NSTimeInterval? {

        // 实时调整当前第一个显示的Cell日期为导航栏标题日期
        currentDate = (tableView.visibleCells.first as? CourseTableViewCell)?.model?[0].end
    }
    public func tableView(tableView: UITableView, heightForHeaderInSection section: Int) -> CGFloat {
        return 140
    }

    
    
    // MARK: - Components
    /// "跳转最近的未上课程"按钮
    private lazy var goTopButton: UIButton = {
        let button = UIButton()
        button.setBackgroundImage(UIImage(named: "goTop"), forState: .Normal)
        button.addTarget(self, action: #selector(CourseTableViewController.scrollToToday), forControlEvents: .TouchUpInside)
        button.hidden = true
        return button
    }()
    lazy var tableView: UITableView = {
