如何仅在左下角,右下角和左上角的textview中设置角半径？
let rectShape = CAShapeLayer()
rectShape.backgroundColor = UIColor.redColor().CGColor
rectShape.bounds = messages.frame
rectShape.position = messages.center
rectShape.path = UIBezierPath(roundedRect: messages.bounds, byRoundingCorners: .BottomLeft | .TopRight, cornerRadii: CGSize(width: 20, height: 20)).CGPath
messages.layer.addSublayer(rectShape)
这段代码创建了两个rect.我不知道为什么.