[iOS][swift]UILabel字體顏色漸層

extension UILabel{
    func GradientLabel(_ colors: [Any]? , isVertical : Bool, locations: [NSNumber]? = [0.0, 1.0]) {
        for sub:UIView in self.subviews {
            if sub.tag == 2 {
                sub.removeFromSuperview()
            }
        }
        
        let containerView = UIView.init(frame: self.bounds)
        containerView.tag = 2
        self.addSubview(containerView)
        
        let label = UILabel.init(frame: self.bounds)
        label.text = self.text
        label.font = self.font
        label.textAlignment = self.textAlignment
        containerView.addSubview(label)
        
        let gradientLayer = CAGradientLayer()
        gradientLayer.colors = colors
        gradientLayer.startPoint = CGPoint(x: 0, y: 0)
        gradientLayer.endPoint = isVertical ? CGPoint(x: 0, y: 1) : CGPoint(x: 1, y: 0)
        gradientLayer.locations = locations//[0.0, 1.0]
        gradientLayer.frame = label.frame
        containerView.layer.insertSublayer(gradientLayer, at: 0)
        gradientLayer.mask = label.layer
        
    }
}