addSubview到UISlider之后的tableViewCell

Question

https://www.dropbox.com/s/jy1p4a9ohp2c2bx/Screenshot%202017-12-10%2019.29.01.png?dl=0

我正在尝试在跟随uislider的tableviewcell内创建一个标签。如果我不将标签放在tableviewcell中，这一切都有效。但是当试图将标签作为子视图添加到单元格时，它将不会跟随滑块。知道我在这里缺少什么吗？

@objc func sliderValueChanged(_ sender: UISlider) {
    let value = sender.value
    sender.setValue(Float(lroundf(value)), animated: true)
    ratingValue = Int(sender.value)
    ratingLabel.text = String(ratingValue)

    let cell = self.addRecordTableView.cellForRow(at: IndexPath(row: 8, section: 0)) as! RatingCell
    cell.addSubview(ratingLabel)
    ratingLabel.center = setUISliderThumbValueWithLabel(slider: sender)
}

@objc func setUISliderThumbValueWithLabel(slider: UISlider) -> CGPoint {
    let slidertTrack : CGRect = slider.trackRect(forBounds: slider.bounds)
    let sliderFrame : CGRect = slider.thumbRect(forBounds: slider.bounds, trackRect: slidertTrack, value: slider.value)
    return CGPoint(x: sliderFrame.origin.x + slider.frame.origin.x + 12, y: slider.frame.origin.y - 30)
}