UISlider滑动条的高度系统默认给我们设定了，没有办法进行改变。可是，我们的设计又是需要改变这个高度的，怎么办呢？这个时候，我们可以写一个UISlider的子类，重写四个方法就能实现了。

//
//  CustomSlider.swift
//  CustomSlider
//
//  Created by iOS on 2018/4/4.
//  Copyright © 2018年 weiman. All rights reserved.
//

import UIKit

class CustomSlider: UISlider {
    
    var height: CGFloat = 0.0

    override func minimumValueImageRect(forBounds bounds: CGRect) -> CGRect {
        return self.bounds
    }
    
    override func maximumValueImageRect(forBounds bounds: CGRect) -> CGRect {
        return self.bounds
    }
    // 控制slider的宽和高，这个方法才是真正的改变slider滑道的高的
    override func trackRect(forBounds bounds: CGRect) -> CGRect {
        let rect = super.trackRect(forBounds: bounds)
        return CGRect.init(x: rect.origin.x, y: (bounds.size.height-height)/2, width: bounds.size.width, height: height)
    }
    // 改变滑块的触摸范围
    override func thumbRect(forBounds bounds: CGRect, trackRect rect: CGRect, value: Float) -> CGRect {
        return super.thumbRect(forBounds: bounds, trackRect: rect, value: value)
    }

}

使用：

lazy var slider: CustomSlider = {
        $0.setThumbImage(#imageLiteral(resourceName: "sliderThumbImage"), for: .normal)
        $0.height = 5 //设置高度
        $0.maximumTrackTintColor = .clear
        $0.minimumTrackTintColor = UIColor(red: 174/255.0, green: 119/255.0, blue: 255/255.0, alpha: 1.0)
        $0.addTarget(self,
                     action: #selector(sliderTouchDown(slider:)),
                     for: .touchDown)
        $0.addTarget(self,
                     action: #selector(sliderEnd(slider:)),
                     for: .touchUpInside)
        return $0
    }( CustomSlider() )

效果：

image.png