在块中应用渐变

Question

这就是我想要的（从黄色一直到顶部，颜色应该是红色）：

现在我可以创建UIView并填充块，但是我很难在每个块中淡入正确的颜色。这可以复制粘贴到游乐场：

import UIKit

class Divider: UIView{
    var blocks: CGFloat = 10
    override func draw(_ rect: CGRect) {
        let spaceBetween = frame.height / blocks
        for i in 0...Int(blocks) - 2{
            let bezierPath = UIBezierPath()
            UIColor.blue.setStroke()
            bezierPath.lineWidth = 1
            bezierPath.move(to: CGPoint(x: 0, y: spaceBetween + spaceBetween * CGFloat(i)))
            bezierPath.addLine(to: CGPoint(x: frame.width, y: spaceBetween + spaceBetween * CGFloat(i)))
            bezierPath.stroke()
        }
    }
    func fill(level: Int){

        let start = 255/blocks * (blocks - CGFloat(level - 1))
        //I am confused on the endColor and beginColor
        let endColor = UIColor(red: start/255, green: start/255, blue: 0, alpha: 1).cgColor
        let beginColor = UIColor(red: start/255, green: start/255, blue: 0, alpha: 1).cgColor
        let spaceBetween = frame.height / (blocks)
        let layer = CAGradientLayer()
        layer.frame = CGRect(x: 0, y: frame.height - (spaceBetween * CGFloat(level)), width: frame.width, height: spaceBetween)
        layer.colors = [endColor, beginColor]
        layer.locations = [0.0, 1.0]
        self.layer.addSublayer(layer)
    }
    override func layoutSubviews() {
        super.layoutSubviews()
        backgroundColor = .green

    }
}

let view = Divider(frame: CGRect(x: 0, y: 0, width: 50, height: 100))
view.fill(level: 1)
view.fill(level: 2)
view.fill(level: 3)
view.fill(level: 4)

如何确保顶部块是红色的，底部块是黄色的，并且它之间的所有内容都很好地消失了？