ios view添加渐变色

        let view = UIView(frame: CGRect(x: 100, y: 100, width: 100, height: 100))
        let gradientLayer = CAGradientLayer()
        //默认是上下渐变，添加startPoint，endPoint修改
        gradientLayer.startPoint = CGPoint(x: 0, y: 0.5)
        gradientLayer.endPoint = CGPoint(x: 1, y: 0.5)
        gradientLayer.frame = view.bounds
        gradientLayer.colors = [UIColor.red.cgColor, UIColor.yellow.cgColor]
        gradientLayer.cornerRadius = 25
//        view.layer.addSublayer(gradientLayer)
        view.layer.insertSublayer(gradientLayer, at: 0)