Tableview没有数据标签页边距不起作用

Question

当表格视图中没有数据时，我具有以下代码来显示标签：

        let noDataLabel: UILabel = UILabel(frame: CGRect(x: 30, y: 30, width: tableView.bounds.size.width-60, height: tableView.bounds.size.height-60))
        noDataLabel.numberOfLines = 0
        var message = ""
        if segmentedControl.selectedSegmentIndex == 1 {
            message = "There are no active timers to display. \n\nGo back to the 'All' page to start a timer. If you have no timers, click the '+' button in the top right hand corner of the screen to add one."
        }
        else {
            message = "There are no timers to display. Add a timer by clicking the '+' button in the top right hand corner of the screen."
        }
        noDataLabel.text = message
        noDataLabel.textColor = UIColor.black
        noDataLabel.textAlignment = .center
        tableView.backgroundView = noDataLabel
        tableView.separatorStyle = .none

但是，标签没有插入物。我该如何解决？