1.创建三个滑竿（UISlider)

• 声明为全局变量

   var redslider = UISlider()
       var greenslider = UISlider()
        var blueslider = UISlider()
  

• 初始化及设置其属性

    redslider = UISlider()
        redslider.frame=CGRect(x: 100, y: 50, width: 200, height: 60)
        self.view.addSubview(redslider)
        redslider.maximumValue = 255
        redslider.minimumValue = 0
        redslider.maximumTrackTintColor = UIColor.red
        redslider.minimumTrackTintColor = UIColor.red
        redslider.addTarget(self, action: #selector(changViewColor), for: .valueChanged)
        
        greenslider = UISlider()
        greenslider.frame = CGRect(x: 100, y: 130, width: 200, height: 60)
        self.view.addSubview(greenslider)
        greenslider.maximumValue = 255
        greenslider.minimumValue = 0
        greenslider.maximumTrackTintColor = UIColor.green
        greenslider.minimumTrackTintColor = UIColor.green
        greenslider.addTarget(self, action: #selector(changViewColor), for: .valueChanged)
        
        blueslider = UISlider()
        blueslider.frame=CGRect(x: 100, y: 210, width: 200, height: 60)
        self.view.addSubview(blueslider)
        blueslider.maximumValue = 255
        blueslider.minimumValue = 0
        blueslider.maximumTrackTintColor = UIColor.blue
        blueslider.minimumTrackTintColor = UIColor.blue
        blueslider.addTarget(self, action: #selector(changViewColor), for: .valueChanged)
  

2. 写一个方法，实现更改视图颜色（让每一个滑竿点击事件都执行这个方法）

func changViewColor(){
        let color = UIColor (colorLiteralRed: redslider.value/255.0, green: greenslider.value/255.0, blue: blueslider.value/255.0, alpha: 1.0)
        self.view.backgroundColor = color
    }

3.效果图