自定义 UISlider 拇指图标:拖动时如何阻止拇指图标恢复为默认圆形图标?

Customizing UISlider thumb icon: How to stop thumb icon from reverting back to default circle icon when drag?

我想将我的 UISlider 的拇指自定义为我制作的矩形图标。我已经设法做到了这一点。问题是当我拖动 UISlider 时它变回默认的圆形图标。

如何设置缩略图使其始终保持为自定义矩形图标,即使在我拖动它时也是如此?

我已经详细介绍了我的代码并包含了一个 link 这样您就可以在下面看到我在说什么。

class DrawViewController: UIViewController {    
    var heightSlider: UISlider = UISlider()        
    var fontColor: UIColor = UIColor(red:0.91, green:0.91, blue:0.91, alpha:1.0)
    var barButtonColor: UIColor = UIColor(red:0.03, green:0.25, blue:0.51, alpha:1.0)

    override func viewDidLoad() {
        super.viewDidLoad()

        heightSlider = UISlider(frame: CGRectMake(0, 20, 98, 31))
        heightSlider.minimumTrackTintColor = barButtonColor
        heightSlider.maximumTrackTintColor = fontColor
        heightSlider.thumbTintColor = barButtonColor
        heightSlider.setThumbImage(UIImage(named: "blueSliderThumbHeight")!, forState: .Normal)

        self.view.addSubview(heightSlider)
    } 
}

To see my app/what I'm talking about

我只需要删除行 heightSlider.thumbTintColor = barButtonColor

class DrawViewController: UIViewController {    
    var heightSlider: UISlider = UISlider()        
    var fontColor: UIColor = UIColor(red:0.91, green:0.91, blue:0.91, alpha:1.0)
    var barButtonColor: UIColor = UIColor(red:0.03, green:0.25, blue:0.51, alpha:1.0)

    override func viewDidLoad() {
        super.viewDidLoad()

        heightSlider = UISlider(frame: CGRectMake(0, 20, 98, 31))
        heightSlider.minimumTrackTintColor = barButtonColor
        heightSlider.maximumTrackTintColor = fontColor
        heightSlider.thumbTintColor = barButtonColor //delete this line!
        heightSlider.setThumbImage(UIImage(named: "blueSliderThumbHeight")!, forState: .Normal)

        self.view.addSubview(heightSlider)
    } 
}