swift渐变之CAGradientLayer

        let gradient:CAGradientLayer = CAGradientLayer.init()
        gradient.frame = CGRect.init(x: 0, y: 0, width: 375, height: 100);//CAGradientLayer的控件大小
        gradient.colors = [UIColor.red.cgColor,UIColor.yellow.cgColor,UIColor.green.cgColor]//渐变颜色
        gradient.locations = [0.2,0.5,0.8]//渐变起始位置
        gradient.startPoint = CGPoint.init(x: 0, y: 0)
        gradient.endPoint = CGPoint.init(x: 1, y: 0)
        let view:UIView = UIView.init(frame: CGRect.init(x: 0, y: 300, width: 300, height: 300))
        view.layer.addSublayer(gradient)
        self.view?.addSubview(view)

           gradient.endPoint = CGPoint.init(x: 1, y: 1)