iOS控件某个边圆角

let maskPath = UIBezierPath(roundedRect: confirmContentV.bounds, byRoundingCorners: [.topLeft,.topRight], cornerRadii: CGSize(width: 18,height: 18))
let maskLayer = CAShapeLayer()
maskLayer.frame = confirmContentV.bounds
maskLayer.path = maskPath.cgPath
view.layer.mask = maskLayer