如何自定义渐变轨道高度和透明度的iOS UISlider

import UIKit

class CustomSlider: UISlider {
    
    override func drawRect(rect: CGRect) {
        // 绘制自定义的轨道
        let trackRect = self.trackRectForBounds(self.bounds)
        let trackPath = UIBezierPath(roundedRect: trackRect, cornerRadius: trackRect.height / 2)
        
        // 创建渐变
        let gradient = CAGradientLayer()
        gradient.frame = trackRect
        gradient.colors = [UIColor.red.cgColor, UIColor.blue.cgColor] // 设置渐变的颜色
        gradient.opacity = 0.5 // 设置渐变的透明度
        
        // 将渐变添加到轨道上
        self.layer.insertSublayer(gradient, below: self.currentThumbImage?.layer)
        
        // 绘制轨道
        trackPath.lineWidth = trackRect.height
        trackPath.stroke()
    }
    
    override func trackRectForBounds(bounds: CGRect) -> CGRect {
        // 自定义轨道的高度和宽度
        let customBounds = CGRect(x: bounds.origin.x, y: bounds.origin.y, width: bounds.width, height: 10)
        return customBounds
    }
}

let customSlider = CustomSlider(frame: CGRect(x: 0, y: 0, width: 200, height: 30))
view.addSubview(customSlider)