为什么 UIViews 背景颜色没有更新？

Switch 语句有效但不会重置视图背景颜色等。

我有一个UIImage（图标）和一个UIButton嵌入在UIView（自定义类型DropShadowCircleView）中，如下图所示。

当步行按钮被点击一个var navigationOption被设置为walking或driving并且setupNavigationSelectionView()被执行。

问题是：开关的“行走”案例完美运行，但“驱动”案例不会将UIView图标色调颜色重新设置为原始设置，例如；背景颜色等。任何想法为什么？

func setupNavigationSelectionView(){

        switch navigationOption {

        case "walking":
            walkingBg.setGradientBackground(colourOne: softGreen, ColourTwo: softBlue)
            walkingBg.layer.cornerRadius = walkingBg.frame.width / 2
            walkingBg.clipsToBounds = true
            walkingIcon.tintColor = #colorLiteral(red: 0, green: 0, blue: 0, alpha: 1)

        case "driving":
            walkingBg.backgroundColor = #colorLiteral(red: 0, green: 0, blue: 0, alpha: 1)
            walkingBg.layer.cornerRadius = walkingBg.frame.width / 2
            walkingBg.clipsToBounds = true
            walkingIcon.tintColor = #colorLiteral(red: 1.0, green: 1.0, blue: 1.0, alpha: 1.0)

        default:
            break

        }
}

编辑：这是我的DropShadowCircleView班级

class DropShadowCircleView: UIView {

    override func awakeFromNib() {

        setupView()
        super.awakeFromNib()

    }

    func setupView(){
        self.layer.shadowOpacity = 0.50
        self.layer.shadowRadius = 20
        self.layer.shadowColor = UIColor.black.cgColor
        self.layer.cornerRadius = self.frame.width / 2


    }

}

编辑：这是我的setGradientBackground功能，它在一个扩展文件中UIView

func setGradientBackground(colourOne: UIColor, ColourTwo: UIColor) {

        let gradientLayer = CAGradientLayer()
        gradientLayer.frame = bounds
        gradientLayer.colors = [colourOne.cgColor, ColourTwo.cgColor]
        gradientLayer.locations = [0.0, 1.0]
        gradientLayer.startPoint = CGPoint(x: 1.0, y: 1.0)
        gradientLayer.endPoint = CGPoint(x: 0.0, y: 0.0)

        layer.insertSublayer(gradientLayer, at: 0)
    }