View頂部設置圓角/部分圓角

   CAShapeLayer *styleLayer = [CAShapeLayer layer];

    UIBezierPath *shadowPath = [UIBezierPath bezierPathWithRoundedRect:self.comView.bounds byRoundingCorners:(UIRectCornerTopLeft|UIRectCornerTopRight)    cornerRadii:CGSizeMake(8.0, 8.0)];

    styleLayer.path = shadowPath.CGPath;

    self.comView.layer.mask = styleLayer;