[SWIFT]UIView 상단 Gradient 효과 주기(채팅창 상단)

UIView 상단 아래서 위로 점점 흐려지게 효과 주기. 보통 채팅창에 많이 사용함

let chatViewGradient = CAGradientLayer()
chatViewGradient.frame = CGRect(x: 0, y: 0, width: self.chattingBrigeWebView.frame.width, height: self.chattingBrigeWebView.frame.height)
chatViewGradient.colors = [UIColor.hexStringToUIColor(hex: "#FFFFFF", alpha: 0.0).cgColor,
                           UIColor.hexStringToUIColor(hex: "#FFFFFF", alpha: 1.0).cgColor]
        
//chatViewGradient.locations = [0.0, 0.3, 0.98, 1.0]
chatViewGradient.locations = [0.0, 0.3]
self.chattingBrigeWebView.layer.mask = chatViewGradient