// 左上和右上为圆角

    UIBezierPath *cornerRadiusPath = [UIBezierPath bezierPathWithRoundedRect:self.contentBGView.bounds byRoundingCorners:UIRectCornerTopRight | UIRectCornerTopLeft cornerRadii:CGSizeMake(18, 18)];

    CAShapeLayer*cornerRadiusLayer = [ [CAShapeLayeralloc]init];

    cornerRadiusLayer.frame=self.contentBGView.bounds;

    cornerRadiusLayer.path= cornerRadiusPath.CGPath;

    self.contentBGView.layer.mask= cornerRadiusLayer;